Container provided with metallic cover and method and apparatus for manufacturing the same

ABSTRACT

This invention relates to a container (10) provided with a metallic cover comprising a plastic container (14) provided with a flanged portion (15) and a metallic cover (11) provided with a peripheral edge portion (12) and having an improved reservation property obtained by improving a material of the container body (14) and the shape thereof, also relates to a method for manufacturing a container provided with a metallic cover comprising the steps of mounting a container body (214) provided with a flanged portion (215) in a recess (267a) of a retainer (267), conveying the container body (214) mounted in the recess (267a) of the retainer (267) and the metallic cover (211) to a seaming device (256), seaming the peripheral portion (212) of the metallic cover (211) to the flanged portion (215) of the container body (214) by the seaming device (256), and discharging the seamed container provided with the metallic cover from the seaming device (256), and further relates to a press-cut device which includes a vertically reciprocating intermediate bed (313) and an upper stationary table (315) disposed above the intermediate bed (313) and in which a pressing device (321) and a cutting device (323) are secured to the intermediate bed (313) and the stationary table (315) and a conveyer (317) is arranged between the pressing device (321) and the cutting device (323).

This is a Division of application Ser. No. 07/445,677 filed asPCT/JP89/00331, Mar. 29, 1989 now U.S. Pat. No. 5,257,709.

TECHNICAL FIELD

This invention relates to a container comprising a plastic body and ametallic cover and to a method and apparatus for manufacturing thecontainer.

BACKGROUND OF THE INVENTION

Metallic containers, for example, metallic cans, have various shapes andcan be classified into three-piece cans and two-piece cans. Thethree-piece can is called a tinplate-soldered can which has a structurein which a cylindrical can body, a top or cover, and an end are doubleseamed and sealed. The two-piece can is called a tinplate-pressed canwhich has a structure in which a can body and an end portion (containerbody) are formed integrally and a cover is double seamed around the rimof the integral container body to seal the same.

These metallic cans are used as food packaging containers for packagingvarious foods, juices, soft drinks, dry foods and the like are thusrigid containers of particular excellence in sealing and preservationproperties. However, metallic cans have the following points to beimproved.

(1) There is a limitation to making the weight light because of thenature of the metallic can;

(2) There is no self-restorative capability if the can is once crushedunder an impact and the can is deformed;

(3) High energy cost is required for manufacturing the metallic can incomparison with a plastic container;

(4) The display effect of the outer appearance of the container cannotbe freely changed in case the container is made of a metallic materialand the display is only carried out by printing operation; and

(5) It is impossible to manufacture a transparent container the contentsof which can be verified without opening the container.

For solving these problems or drawbacks of the conventional metalliccans described hereinabove, a container with a metallic cover in which ametallic cover is secured to a plastic container body has beenconceived.

In a case where a metallic cover is secured to the plastic containerbody, the peripheral edge portion of the metallic cover is seamed to aflanged portion of the container body.

As described above, the container with the metallic cover is constructedby seaming the metallic cover to the flange of the plastic containerbody.

In addition, it is required for the plastic container body to have aprecision strength against the flange seaming force, a gas-barrierproperty capable of improving a content reserving function and anadequate strength of a shell portion thereof.

However, there has not been proposed ay container provided with ametallic cover sufficiently attaining or achieving the above describedfunctions, and technology for the manufacturing method and apparatus forsuch container have been not yet established.

SUMMARY OF THE INVENTION

An object of this invention is to provide a container provided with ametallic cover and comprising a plastic container body and a metalliccover which can be manufactured simply and air-tightly and to provide amethod and apparatus for manufacturing such container provided with themetallic cover.

(1) A first feature of this invention resides in a container providedwith a metallic cover comprising a plastic container body provided withan upper opening around which a flanged portion is formed and a metalliccover provided with a peripheral portion which is seamed to the flangedportion and characterized in that the container body is formed of alaminated sheet member having a gas-barrier property and an injectedfusible resin.

(2) A second feature of this invention resides in a container providedwith a metallic cover comprising a plastic container body provided withan upper opening around which a flanged portion is formed and a metalliccover provided with a peripheral portion which is seamed to the flangedportion and characterized in that the container body is formed byeffecting a sheet forming treatment to a laminated sheet member having agas-barrier property.

(3) A third feature of this invention resides in a container providedwith a metallic cover comprising a plastic container body provided withan upper opening around which a flanged portion is formed, a metalliccover provided with a cover body for sealing the end opening and aperipheral portion connected to the cover body through a shoulderportion and adapted to seam the flanged portion, and a sealing membercoated annularly on a seamed portion between the flanged portion of thecontainer body and the peripheral portion of the metallic cover andcharacterized in that the sealing member is coated at least to a portionnear the shoulder portion of the metallic cover.

(4) A fourth feature of this invention resides in a container providedwith a metallic cover comprising a plastic container body provided withan upper opening around which a flanged portion is formed and a metalliccover provided with a peripheral portion which forms a double seamedportion in association with the flanged portion and characterized inthat the seamed width of the double seamed portion is made more than 0.5(3M+2P) and less than (3M+2P), where P is a thickness of the flangedportion before the seaming and M is a thickness of the peripheralportion before the seaming.

(5) A fifth feature of this invention resides in a container providedwith a metallic cover comprising a plastic container body provided withan upper opening around which a flanged portion is formed and a metalliccover provided with a peripheral portion which is seamed to the flangedportion and characterized in that a deoxidizer is applied to an innersurface of the metallic cover or an inner surface of the container body.

(6) A sixth feature of this invention resides in a method comprising thesteps of thermally forming a plastic container body provided with aflanged portion formed by sheet forming a laminated material having agas-barrier property, pressing the flanged portion between a press malemold half and a press female mold half to reduce the thickness of theflanged portion, cutting the peripheral portion of the flanged portionbetween a cutting male mold half and a cutting female mold half to setthe width of the flanged portion to a predetermined value, the methodbeing characterized in that a guide having an outer configurationcorresponding to the inner shape of the container body is inserted intothe container body during at least one of the pressing and cutting stepsand the pressing or cutting step is performed after the insertion of theguide into the container body.

(7) A seventh feature of this invention resides in a method ofmanufacturing a container provided with a metallic cover comprising thesteps of mounting a plastic container body provided with a flangedportion to a recessed portion of a retainer having a shape correspondingto an outer configuration of the bottom surface of the container body,conveying the container body mounted in the recessed portion of theretainer and a metallic cover having a peripheral portion fitted in theflanged portion of the container body to a rolling and seaming unit,roll-seaming the peripheral portion of the metallic cover to the flangedportion of the container body by means of the rolling and seaming unit,and discharging the seamed container provided with the metalliccontainer from the rolling and seaming unit.

(8) An eighth feature of this invention resides in a method ofmanufacturing a container provided with a metallic body comprising thesteps of packaging a content into a plastic container body provided witha flanged portion, seaming a peripheral portion of the metallic cover tothe flanged portion of the container body, and heating and sterilizingthe seamed container body and the metallic cover so as to make constanta pressure difference between the inner pressure of the container bodyand the outer pressure thereof.

(9) A ninth feature of this invention resides in a press-cut apparatuscomprising an intermediate bed vertically movable in a reciprocatingmanner and an upper stationary table disposed above the intermediatebed, a press unit for pressing a flanged portion of a plastic containerbody by mounting one of press male and female mold halves to theintermediate bed and mounting the other one of press male and femalemold halves, a cutting unit for cutting the outer periphery of theflanged portion of the container body by mounting one of cut male andfemale halves to the intermediate bed and mounting the other one of cutmale and female halves, and a conveying unit disposed between the pressunit and the cut unit for conveying the container body from the pressunit to the cut unit.

(10) A tenth feature of this invention resides in a container seamingapparatus comprising a rotary lifter which is supported on a verticallymovable supporting cylinder and on which a container provided with ametallic cover is rested, a rotary chuck disposed above the rotarylifter and adapted to press hold the container provided with themetallic cover between the rotary lifter and the rotary chuck, and aplurality of seaming rolls disposed external to the rotary chuck andadapted to seam the container provided with the metallic cover, a straingauge being further mounted on the outer surface of the supportingcylinder so that the clamping force of the seaming rolls can be detectedby a signal from the strain gauge.

(11) An eleventh feature of this invention resides in a containerseaming apparatus comprising a rotary lifter which is supported on avertically movable supporting rod and on which a container provided witha metallic cover is rested, a rotary chuck disposed above the rotarylifter and adapted to press hold the container provided with themetallic cover between the rotary lifter and the rotary chuck, and aplurality of seaming rolls disposed external to the rotary chuck andrespectively revolved about the container provided with the metalliccover, an annular load meter being further mounted on the outer surfaceof the supporting rod of the lifter so that the pressing force betweenthe lifter and the chuck can be detected by a signal from the loadmeter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 7 are views showing a container provided with a metalliccover having a container body made of a container blank in the firstembodiment of the container provided with the metallic cover accordingto this invention;

FIGS. 8 to 12 are views showing a container provided with a metalliccover having a container body provided with four pillars in the firstembodiment of the container provided with the metallic cover accordingto this invention;

FIGS. 13 to 15 are views showing a container provided with a metalliccover having a container body made of a specific thermally fusible resinin the first embodiment of the container provided with the metalliccover according to this invention;

FIGS. 16 to 19 are views showing a container provided with a metalliccover having a container body provided with a flanged portion having asubstantially uniform thickness in the second embodiment of thecontainer provided with the metallic cover according to this invention;

FIGS. 20 to 22 are views showing a container provided with a metalliccover having a container body formed of a laminated member including anethylene vinyl alcohol copolymer containing a drying agent in the secondembodiment of the container provided with the metallic cover accordingto this invention;

FIGS. 23 to 26 are views showing a container provided with a metalliccover having a container body provided with a flanged portion having abase end on the surface of which an annular recess is formed in thesecond embodiment of the container provided with the metallic coveraccording to this invention;

FIGS. 27 to 29 are views showing a container provided with a metalliccover having a container body formed of a sealing member of a heatsealing member in the third embodiment of the container provided withthe metallic cover according to this invention;

FIGS. 30 to FIGS. 34(a), 34(b), 34(c), 34(d), and 34(e) are viewsshowing a container provided with a metallic cover having a containerbody formed of a sealing member of a rubber sealing member of the thirdembodiment of the container provided with the metallic cover accordingto this invention;

FIGS. 35 and 36 are views showing a container provided with a metalliccover having a container body provided with a seaming portion having aseam width in a specific shape in the fourth embodiment of the containerprovided with the metallic cover according to this invention;

FIGS. 37 to 41 are views showing a container provided with a metalliccover having a container body provided with a seaming portion havingseam width and height of the specific lengths in the fourth embodimentof the container provided with the metallic cover according to thisinvention;

FIGS. 42 and 43 are views showing a container provided with a metalliccover of the fifth embodiment according to this invention in which adeoxidizer is secured thereto;

FIGS. 44 to 48 represent the first embodiment of a method ofmanufacturing a container body of a container provided with a metalliccover, in which a guide is inserted during a pressing process or cuttingprocess;

FIGS. 49 to 51 represent the first embodiment of a method ofmanufacturing a container provided with a metallic cover according tothis invention, in which a retainer is utilized;

FIGS. 52 and 53 represent the second embodiment of a method ofmanufacturing a container provided with a metallic cover according tothis invention, in which the container is heat sterilized under thecondition that the pressure difference between the inner and outerpressures of the container is made constant;

FIGS. 54 to 56 show a press cut device provided with an intermediate bedof the first embodiment of an apparatus for manufacturing a containerprovided with a metallic cover according to this invention;

FIGS. 57 and 58 show a heat press device provided with a liner of thefirst embodiment of the apparatus for manufacturing a container providedwith a metallic cover according to this invention;

FIGS. 59 to 63(a), 63(b) and 63(c) show a container seaming deviceprovided with a rotary lifter and a rotary chuck of the secondembodiment of an apparatus for manufacturing a container provided with ametallic cover according to this invention; and

FIGS. 64 to 66 show a container seaming device provided with revolvingseaming rolls of the second embodiment of the apparatus formanufacturing the container provided with the metallic cover accordingto this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

§1. First Embodiment of Container with Metallic Cover (A containerhaving container body formed of a laminated sheet of gas-barrierproperty and an injected thermally fusible resin)

1-1 A container provided with a metallic cover having a container bodymade of a blank in shape of a container

(1-1-1 Basic Structure 1)

FIGS. 1 to 5 represent a basic structure of a container provided with ametallic cover having a container body made of a blank in shape of acontainer.

As shown in FIG. 4, a container provided with a cover is generallydesignated by reference numeral 10 and is constructed by roll-seaming aperipheral portion 12 of a metallic cover 11 made of an aluminum ortinplate metal to a flanged portion 15 of a plastic container body 14.

A method of manufacturing the container 10 provided with the metalliccover will be described in detail hereunder.

First, as shown in FIG. 1, a heated laminated sheet is vacuum formed bya pair of thermoforming core provided with a plurality of continuousrecesses and injection molding cavity, not shown, so as to provide athermally formed product 20 formed of plural blank 21 each in shape of acontainer and blanks 22 each in shape of a flat plate.

The product 20 may be formed by vacuum formation, pressure formation,plug assist formation method or a manner in combination of thesemethods.

The laminated sheet has been preliminarily heated before the insertionof the thermoforming core 30 and the vacuum formation is carried out bydrawing the air through an air ventilation port 31 formed to thethermoforming core 30.

A laminated sheet material having a gas-barrier property is utilized forthe described laminated sheet having, for example, a layer structure ofpolypropylene (PP)/bonded layer/ethylene vinyl alcohol copolymer(EVOH)/bonded layer/polypropylene (PP); polystyrene/bondedlayer/ethylene vinyl alcohol copolymer/bonded layer/polystyrene;polyethylene terephthalate (PET)/polyallylate/polyethyleneterephthalate; polyallylate/polyethylene terephthalate/polyallylate; orthe like.

In these materials, the ethylene vinyl alcohol copolymer particularlyhas a superior gas-barrier property. A drying agent may be mixed withthe ethylene vinyl alcohol copolymer and, in such case, a water contentmixed with the ethylene vinyl alcohol copolymer is removed to therebysurely prevent the gas-barrier property from lowering.

In the next step, as shown in FIG. 2, a cutter 32 is lowered from theupper portion of the product 20 on the thermoforming core 30 to therebycut out the laminated sheet by the cutter 32 and the core 30 to form theproducts 20 with the container blanks 21 remaining and the plate blanks22 removed.

The cutter 32 is thereafter elevated upwardly and an injection moldingcavity 17 is mounted from an upper portion thereof in substitution forthe cutter 32 (FIG. 3).

In the succeeding step, a thermally fusible resin 28 is injected intothe core 30 through an injection port 17a provided for the injectionmolding cavity 17. A part of the thermally fusible resin 28 injectedalong the peripheral edge of the container blank 21 forms a flangedportion 15 of the container body 14 and a part of the thermally fusibleresin 28 injected along the surface of a shell portion of the containerbody forms the container body 14 including a shell portion 14a and abottom portion 14b (FIG. 4). Portions of the thermoforming core 30 andthe injection molding cavity 17 forming the flanged portion 15 are matedwith each other with a gap therebetween throughout from the base endportions and the front end portions thereof to form the flanged portion15 having substantially uniform thickness throughout from the base endportion and the front end portion thereof.

As a material for the thermally fusible resin 28 is listed up apolypropylene, polyethylene, polystyrene, polycarbonate, nylon,polyethylene terephthalate or the like, but any kind of thermoplasticresin may be generally utilized as the thermally fusible resin 28.

It is necessary for the thermally fusible resin 28 to be fused andsecured to the resin forming the surface of the laminated sheetcontacting the resin 28, so that the polypropylene will have to beselected when the surface of the laminated sheet is the polypropyleneand, on the other hand, in a case where the polyethylene terephthalateis selected for a thermally fusible resin 28, it will be desirable toselect a resin of the polyethylene terephthalate type for the surface ofthe laminated sheet.

The thus formed container body 14 is filled with contents 19. Then theperipheral edge portion 12 of the metallic cover 11 is seamed by doubleseaming fashion to the flanged portion 15 of the container body 14 tothereby form the container 10 provided with the metallic cover.

With the formation of the container 10, it is desired to preliminarilyapply or coat a dust proof top coat (not shown) on the outer surface ofthe metallic cover 11. A coating of a resin such as epoxy resin or vinylresin (not shown) is preliminarily applied on the inner side surface ofthe metallic cover 11 for preventing corrosion of the metallic cover andthe deterioration of nature of the contents.

According to this embodiment, since the flanged portion 15 of thecontainer body 14 is formed by the injection molding method, the formedflanged portion 15 has a thickness and a width of the desired accurateshapes and a predetermined strength. Accordingly, the double seamingprocess of peripheral portion 12 of the metallic cover 11 and theflanged portion 15 can be performed with high precision.

The shell portion 14a and the bottom portion 14b of the container body14 are formed of the container blank 21 made of a laminated sheet havinga predetermined gas-barrier property and the thermally fusible resin 28injected on the surface of the container blank 21, so that the containerbody 14 formed has an improved gas-barrier property and strength.Namely, since the container blank 21 covers with substantially no spacethe shell portion 14a and the bottom portion 14b of the container body14, the thus formed container body has a gas-barrier property largerthan that of a container formed by assembling a plate like laminatedsheet with a space into a cylindrical shape, for example.

Furthermore, the cutting out and removing operation of the plate blank22 and the injection into the container blank 21 can be performed with astate in which the container blank 21 is mounted to the thermoformingcore 30, whereby the container body 14 is smoothly and accuratelyformed.

In the embodiment described above, the thermally fusible resin 28 isinjected on the outer side of the container blank 21 of the laminatedsheet as shown in FIG. 4, but the thermally fusible resin 28 may beinjected in the inner side of the container blank 21 of the laminatedsheet as shown in FIG. 5.

For example, in a case where the laminated sheet is formed ofpolypropylene/bonded layer/ethylene vinyl alcohol copolymer/bondedlayer/polypropylene and the polypropylene is utilized as the thermallyfusible resin 28, when the thermally fusible resin 28 is injected on theinner side of the container blank 21 as shown in FIG. 5, the layers ofthe shell portion 14a and the bottom portion 14b of the container body14 have the layer structures, from the inner side thereof, ofpolypropylene injection layer/polypropylene layer/bondedlayer/ethylene-vinyl alcohol copolymer layer/bonded layer/polypropylenelayer and, accordingly, the gas-barrier property originally endowed forthe ethylene vinyl alcohol copolymer can be exhibited.

Furthermore, in the described embodiment, an example in which theflanged portion 15 has a thickness uniform from the base end portion tothe front end portion thereof, but an annular recess extending in acircumferential direction may be formed to the lower surface of the baseend portion of the flanged portion 15 to thereby facilitate the seamclamping working of the flanged portion.

(Specific Example)

A specific example of the Basic Structure 1 will be described hereunder.

A laminated sheet was cut out so as to vacuum form a container blankhaving an inner diameter of 6.3 mm, a thickness of 35.0 mm and the plateblank 21 was cut out. The average thickness of the cut out plate blank21 was 0.4 mm (comparison example 1). The shell portion 14a and thebottom portion 14b of the container body 14 were further made thick by0.9 mm by carrying out the injection molding operation. The flangedportion was formed so as to have a thickness of 0.3 mm and a width of2.0 mm.

The following results were obtained for this specific example and thecomparison example.

                                      TABLE                                       __________________________________________________________________________                                   Oxygen Permeability                                                           (cc/24 hour: one                                                              container) measured                                                           after opening after                                                    Deformation                                                                          reservation for two                                                    in     days after retort                                                      Vaccum sterilization                                         Laminated Sheet                                                                           Injection                                                                          Seaming                                                                              (120° C. × 40                     __________________________________________________________________________                                   min.)                                          Comparison 1                                                                         PP/EVOH/PP  No   x      1.00                                           Example 1                                                                            PP/EVOH/PP  PP   ∘                                                                        1.00                                                              Outward                                                    Example 2                                                                            PP/EVOH/PP  PP   ∘                                                                        0.10                                                              Inward                                                     Example 3                                                                            PET/polyallylate/PET                                                                      PP   ∘                                                                        --                                                                Outward                                                    __________________________________________________________________________

In this Table 1, the degree of oxygen permeability is a value based onthe measurement reference OXTRAN 100 (ASTM D3985).

(1-1-2 Basic Structure 2)

The basic structure 2 of the container provided with the metallic coverhaving a container body formed of a blank in shape of a container willbe described hereunder with reference to FIGS. 6 and 7.

The basic structure 2 differs from the basic structure 1 merely in theshape of the container body 14 and a method of manufacturing the same.The container body 14 regarding the basic structure 2 will be describedwith reference to FIGS. 6 and 7.

The container body 14 is provided with a shell portion 14a and an upperstepped portion 35 from which the shell portion 14a extends upwardlyobliquely so as to have an increased inner diameter. The flanged portion15 of the container body 14 extends radially outwardly with a slightinclination (with an angle of α as shown in FIG. 7). An annular bottomedge portion 29 is formed to the peripheral edge of the bottom portion14b of the container body so as to extend downwardly with a radius of R.

The manufacturing method of the container body 14 is describedhereunder.

A heated laminated sheet is vacuum formed by the thermoforming core andthe injection molding cavity in a manner described with reference to thebasic structure 1 to thereby form a thermally formed product including aplurality of blanks 21 each in shape of a container and blanks each inshape of a flat plate.

In the next step, the product is taken out from the injection moldingcavity and the plate blanks are cut out and removed by a cutting deviceequipped with a draw-out mold, not shown, having a cutter and ahydraulic shearing device, not shown, whereby only the container blanks21 remain.

The container blanks 21 are then mounted in an injection molding core,not shown, and an injection molding cavity, not shown.

A thermally fusible resin 28 is thereafter injected along the surfaceand the end peripheral edge of the container blank 21 to thereby formthe shell portion 14a and the bottom portion 14b together with theflanged portion 15, thus the container body 14 being formed. In theinjection molding operation, when it is required to inject the thermallyfusible resin 28 on the inner side of the container blank 21, thecontainer blank 21 is mounted on the side of the injection moldingcavity, whereas when it is required to inject the resin 28 on the outerside thereof, the container blank 21 is mounted on the side of theinjection molding core.

According to this embodiment, the container blank covers withsubstantially no space the shell portion 14a and the bottom portion 14bof the container body 14, so that the gas-barrier property of thecontainer body 14 can be improved.

(Concrete Example)

A concrete example of the basic structure 2 will be described hereunder.

The laminated sheet for forming the heat formation product was formed ofpolypropylene (PP) 240μ/bonded layer 40μ/ethylene vinyl alcoholcopolymer (EVOH) 40μ/bonded layer 40μ/polypropylene (PP) 240μ. As thepolypropylene XF 1973 GRADE of CHISSO PETROCHEMICAL CORPORATION wasutilized, as the ethylene vinyl alcohol copolymer EVAL T-102 GRADE ofKURARAY CO. LTD. was utilized, and as the bonded layer ADOMER -QF-500GRADE (MITSUI PETROCHEMICAL INDUSTRIES, LTD.) was utilized.

The heat formation of the laminated sheet was performed by the plugassist pressure vacuum method with the following formation conditions.

Temperature of Cavity: 17° C.

Pre-heating: 150° to 180° C.

Mold Clamping Force: 200 kg/cm²

Air Pressure: 2 kg/cm²

Vacuum Pressure: 760 mmHg

The injection molding operation for the surface and the end peripheraledge of the container blank 21 was performed with the followingconditions.

Injected Resin: Polypropylene of XK 6449 GRADE (MFR 7.0)

Cylinder Temperature: HN 240° C., H1 230° C., H2 220° C., H3 200° C.

Mold Temperature: 70° C. (constant)

Screen Revolution Speed: 70 rpm

Primary Pressure: 70 kgf/cm²

Secondary Pressure: 60 kgf/cm²

Injection Time: 6 sec.

Injection Molding Machine: TOSHIBA IS-80EPN

Mold: One-off Gate-type pin gate

The respective portions of the container body 14 were as follows. Theupper end opening of the shell portion. 14a of the container body 14 hadan inner diameter of 65.3 mm. The inner diameter of the bottom portion14b of the container body 14 was 59.0 mm. The height between the bottomportion 14b and the lower end of the flanged portion 15 was 55.0 mm. Theaverage thickness of the container blank 21 was 0.2 mm and the thicknessand the width of the shell portion 14a and the bottom portion 14b afterthe injection molding were both 1.1 mm.

Furthermore, the flanged portion had a thickness of 0.4 mm and a widthof 1.9 mm. The upper inclination of the flanged portion 15 was 15°(angle a in FIG. 7).

The container 10 provided with the metallic cover formed according tothis embodiment provided a good deformation condition in case of seamingthe container body and the metallic cover and an improved gas-barrierproperty.

(1-1-3 Effects)

According to this invention, since the flanged portion of the containerbody 14 can be formed with a predetermined shape, the double-seamingoperation between the flanged portion 15 and the periphery 12 of themetallic cover 11 can be accurately performed to thereby obtain acontainer 10 provided with a metallic cover having an improved air-tightproperty. In addition, it is possible to improve the gas-barrierproperty and the strength of the container body, so that the container10 provided with the metallic cover manufactured can provide a superiorreservation characteristic for the content 19 and an improved rigidity.

1.2 Container provided with a metallic cover having a container bodywith four pillars

(1-2-1 Basic Structure)

FIGS. 8 to 12 represent a container provided with a metallic coverhaving a container body having four pillars.

Referring to FIG. 8, a container 10 provided with a metallic cover isformed by roll-seaming the peripheral edge 12 of a metallic cover 11 toa flanged portion 15 formed around an upper end opening of a plasticcontainer body 14.

The metallic cover is made of an aluminum metal or tinplate metal andthe inner surface of the metallic cover 11 is preliminarily coated withan epoxy resin.

The container body 14 of the container provided with the metallic coveraccording to this invention will be described hereunder in conjunctionwith FIGS. 9 to 12.

The container body 14 comprises a shell portion 14a, a bottom portion14b and a flanged portion 15. The shell portion 14a and the bottomportion 14b are formed of a sheet blank 26 having a gas-barrier propertyand a thermoplastic resin 28 injected on the surface of the sheet blank26.

The shell portion 14a is provided with four pillars (columnar thickenedportions) 27 and the bottom portion 14b is also provided with aperipheral edge 29 made of a thermoplastic resin 28 and extendingdownwardly.

Each of the pillars 27 protrudes inwardly from the inner surface of theshell portion 14a and has a wall thickness greater than that of theother portion of the shell 14a. The pillar 27 is composed of a portion27a formed by embedding gaps between respective sheet blanks 26a,described later, for the shell portion 14a with the thermally fusibleresin 28 and a portion 27b, in FIG. 7, formed by the thermally fusibleresin 28 applied on the surface of the sheet blank 26. Both the portions27a and 27b have wall thicknesses greater than those of the otherportions of the shell 14a to increase the buckling strength of thecontainer body 14. The portions 27a and 27b of the four pillars 27 arearranged with equal spaces in the circumferential direction, but theportions 27b are arranged at portions apart from a foldable portion 26cof the sheet blank 26 as described hereinafter.

Any type of sheet blanks may be utilized for the sheet blank 26 forforming the container body 14 according to this embodiment as far as theblank sheet is of a gas-barrier construction including a thermoplasticresin coat. However, it is necessary to use the same resin material forthe thermoplastic resin 28 forming an injection molding product and thethermoplastic resin 28 forming the sheet blank 26 or to use a resinmaterial which is thermally fusible. The sheet blank has the basicstructure formed by a laminated sheet of the thermoplastic resincomposed of layers of, from the outer surface to the inner surface ofthe container body 14, polyethylene terephthalate/aluminum foilpolypropylene (CPP), (Dry Laminate); Composed paper (PP)/aluminumfoil/polypropylene (CPP), (Dry Laminate); Polyethyleneterephthalate/vinylidene chloride copolymer/polypropylene (CPP), (DryLaminate); Polyethylene terephthalate/ethylene vinyl alcoholcopolymer/polypropylene (CPP), (Dry Laminate); Polypropylene(OPP)/polyethylene extrusion coating paper/aluminum foil/polypropylene(CPP), (Dry Laminate); Polypropylene (OPP)/polypropylene(CPP)/co-extrusion sheet of polypropylene ethylene vinyl alcoholcopolymer and polypropylene, (Dry Laminate and Heat Laminate)

The sheet blank 26 of the type described above may be formed so as tohave a thickness of the range between 100μ to 800μ. A drying agent maybe mixed with the ethylene vinyl alcohol copolymer of the sheet layerstructures described above. The drying agent acts to remove the watercontent contained in the ethylene vinyl alcohol copolymer to therebyprevent the lowering of the gas-barrier property thereof.

The sheet blank 26 to be utilized for this embodiment has a plate likeshape as shown in FIG. 10 formed by punching out the laminated sheet ofthe type described above.

Namely, the sheet blank 26 is composed of a bottom sheet blank 26bcorresponding to the bottom portion 14b of the container body 14 and ashell sheet blank 26a connected to the bottom sheet blank 26b andcorresponding to the shell portion 14a of the container body 14.

The bottom sheet blank 26b and the shell sheet blank 26a are connectedthrough a connecting foldable blank 26c and the sheet blank 26 isinserted into the mold after folded at the connecting foldable blank26c.

As the thermally fusible resin 28 utilized for the injection molding,polypropylene, polyethylene, polystyrene, polycarbonate, nylon,polyethylene terephthalate, or the like may be listed up, but any kindof thermoplastic resin may be generally utilized. In the injectionmolding operation, when it is required to inject the thermally fusibleresin 28 on the inner side of the sheet blank 26, the thermally fusibleresin 28 for the injection molding operation must be selected fromresins which are fusible to the resin forming the inner surface of thesheet blank 26. Accordingly, the inner surface of the sheet blank 26 isformed of the polypropylene, the polypropylene is selected for thethermally fusible resin 28, whereas when the polyethylene terephthalateis selected for the thermally fusible resin 28, it is desired to formthe inner surface of the sheet blank 26 with the resin of polyethyleneterephthalate type.

(1-2-2 Manufacturing Method)

The manufacturing method of the container 10 provided with the metalliccover will be described hereunder.

The manufacturing method of the container body 14 will be mentionedfirst.

The sheet blank 26 is first set to the core 30 by being attracted by avacuum hole 31 under the vacuuming condition as shown in FIG. 12. Thecore 30 is preliminarily provided with four vertical grooves 39a forforming four pillars 27.

According to this operation, the plate like sheet blank 26 is assembledinto a cubic form with two spaces between the shell sheet blank 26acorresponding to the sheet portion 14a of the container body 14.

The sheet blank 26 mounted on the core 30 as shown in FIG. 12 isinserted into the cavity 17 as it is and the thermally fusible resin 28is introduced into the cavity 17 through a gate 17a. The thermallyfusible resin 28 is injected on the inner surface of the sheet blank 26to thereby form the shell portion 14a, the bottom portion 14b, theflanged portion 15 and the bottom edge portion 29. At the same time, thethermally fusible resin 28 is introduced into the vertical grooves 30aof the core 30 to thereby form the pillars 27. Namely, the pillars 27aare formed at portions corresponding to the two gaps formed in the shellsheet blank 26a by the vertical grooves 30a of the core 30 and thepillars 27b are formed in the shell sheet blank 26a. In this case, aportion which forms the flanged portion of either one of the core 30 orthe cavity 17 is provided with a gap having a uniform width throughoutthe base end portion and the front end portion, so that the formedflanged portion has the uniform thickness throughout the base endportion and the front end portion thereof.

A content 19 is then accommodated in the container body 14 and theperipheral portion 12 of the metallic cover 11 is thereafter seamed tothe flanged portion of the container body 14.

According to this embodiment, the four pillars 27 each having thethickness larger than that of the other portions of the container body14 are formed to the inner surface of the shell portion 14a so as toproject inwardly, so that the buckling strength of the container bodyitself can be improved.

In the foregoing embodiment, there is shown an example in which thethermally fusible resin 28 is injected on the inner surface of the blank26 for forming the container body, but the thermally fusible resin 28may be injected on the outer surface of the blank 26, and in which thevertical grooves 30a are formed in the core 30 to form the pillars 27protruding inwardly from the shell portion 14a, but the vertical groovesmay be formed in the cavity to form the pillars 27 protruding outwardlyfrom the shell portion 14a. Moreover, the number of the pillars are notlimited to four and more than four pillars 27 may be formed. In theexample, the thickness of the flanged portion is formed to besubstantially uniform between the base end portion and the front endportion thereof, but an annular recess extending in the circumferentialdirection may be formed to the lower surface of the base end portion ofthe flanged portion 15 to thereby facilitate the easiness of theroll-seaming operation.

(1-2-3 Concrete Example)

A concrete example according to an embodiment this invention will bedescribed hereunder.

Experimental results with respect to the buckling strength in comparisonof the container body 14 provided with four pillar portions and thatprovided with two pillar portions are shown in the following table.

    ______________________________________                                        Buckling Strength (kg)                                                        Filling                                                                       Temperature   Two Pillars                                                                             Four Pillars                                          ______________________________________                                        20° C. 80        100                                                   60° C. 50        100                                                   ______________________________________                                    

As can be seen from this table, an improved buckling strength can beachieved according to this invention (in which four pillars are formed).

(1-2-4 Effects)

According to this invention, at least four pillar portions 27 eachhaving a thickness larger than that of the other portions of thecontainer body 14 are formed to the shell portion 14a of the containerbody 14, so that the buckling strength of the container body 14 can beimproved and, hence, a container 10 provided with a metallic cover lessdamaged or broken even if dropped can be, forwarded.

1.3 Containers provided with metallic covers each having a containerbody formed of a thermally fusible resin with specific feature

(1-3-1 Basic Structure)

FIGS. 13 to 15 shows a container provided with a metallic cover having acontainer body formed of a thermally fusible resin having a specificfeature.

The container 10 provided-with the metallic cover is formed, asdescribed with respect to the container body provided with four pillarportions in 1.2 described above (FIG. 8), by roll-seaming the peripheraledge 12 of the metallic cover 11 to the flanged portion 15 formed at theupper end opening of the plastic container body 14.

The metallic cover 11 is formed of a plastic or tinplate material and anepoxy resin is preliminarily coated on the inner surface of the metalliccover 11.

The container body 14 of the container 10 provided with the metalliccover according to this invention is shown in FIGS. 13 to 15.

The container body 14 is composed of a flanged portion 15, a shellportion 14a provided with pillar portions 27 and a bottom portion 14bprovided with a bottom edge portion 29.

The flanged portion 15, the pillar portions 27 and the bottom edgeportion 29 are formed of an injected thermally fusible resin 28. Theshell portion 14a and the bottom portion 14b are formed of a sheet blank26 having a gas-barrier property and the thermally fusible resin 28. Thepillar portions 27 are formed, as described hereinafter, by filling gapsformed in a shell sheet blank 26a with the thermally fusible resin 28.The bottom edge portion 29 has an annular shape protruding downwardlyand is adapted to support the container body 14.

Any type or kind of material including a thermoplastic resin coat as faras having the gas-barrier property, may be utilized for forming thesheet blank 26 to be used for forming the container body 14 according tothis embodiment. However, the thermoplastic resin 28 forming aninjection molding product and a resin forming the inner surface of thesheet blank 26 should be formed of the same resin or a thermally fusibleresin. The basic structure of the sheet blank 26 may be formed by alaminated sheet of thermoplastic resins layered in the following orderfrom the outer surface of the container body 14 towards the innersurface thereof.

Polypropylene (OPP)/polyethylene extrusion coating paper/aluminumfoil/polypropylene (CPP), (Dry Laminate); and polypropylene(OPP)/polypropylene (CPP)/polypropylene ethylene vinyl alcoholcopolymer-polypropylene co-extrusion sheet, (Dry Laminate and HeatLaminate)

The sheet blank 26 of the above described structure having a thicknessof 100μ to 800μ may be utilized for the container body 14 according tothis embodiment.

The sheet blank 26 of this embodiment has a flat plate shape formed bypunching out the laminated sheet into the shape shown in FIG. 10 asdescribed with respect to the container body 14 provided with the fourpillar portions of 1.2 described hereinbefore.

Namely, the sheet blank 26 is composed of a bottom sheet blank 26bcorresponding to the bottom portion 14b of the container body 14 and ashell sheet blank 26a corresponding to the shell portion 14a of thecontainer body 14, the shell sheet blank 26a being connected to thebottom sheet blank 26b.

The shell sheet blank 26a and the bottom sheet blank 26b are connectedthrough a foldable portion 26c and the sheet blank 26 is folded at thisfoldable portion 26c so as to be inserted into a mold.

A polypropylene (PP) type resin may be utilized as a thermally fusibleresin 28 which is utilized for the injection molding and, among thepolypropylene type resins, a resin, as the thermally fusible resin 28,only by which the flanged portion 15 and the bottom edge portion 29 ofthe container body 14 having an improved strength can be formed.

(1-3-2 Manufacturing Method)

A manufacturing method of the container 10 provided with the metalliccover will be described hereunder.

A manufacturing method of the container body 14 is first described.,

The sheet blank 26 is first set to the core 30 by sucking the samethrough a vacuuming hole 31 of the core 30 as shown in FIG. 12.

The sheet blank 26 set to the core 30 is thereafter inserted as it isinto the cavity 17 and the thermally fusible resin 28 is then introducedtherein through the gate 17a of the cavity 17. The thermally fusibleresin 28 is hot only injected to form the flanged portion 15, the pillarportions 27 and the bottom edge portion 29 of the container body 14, butalso injected on the surface of the sheet blank 26 inserted into thecavity 17 to thereby form the container body 14.

With the container body 14 thus formed, the flanged portion 15, thepillar portions 27 and the bottom edge portion 29 are formed of thethermally fusible resin 28 and the shell portion 14a and the bottomportion 14b are formed of the outside gas-barrier sheet blank 26 and theinside thermally fusible resin 28.

A content is packaged in the container body 14 and the peripheral edge12 of the metallic cover 11 is thereafter seamed to the flanged portion15 of the container body 14.

(1-3-3 Specific Example)

Specific experimental examples for determining the characteristics ofthe thermally fusible resin 28 to suitable values are shown hereunder.

Some kinds of polypropylene resins having physical properties differentfrom each other as the thermally fusible resins were utilized formanufacturing containers provided with metallic covers, respectively.Thereafter, drop tests were performed with respect to these containerswith metallic covers. The results of the tests are shown in thefollowing table.

                                      TABLE                                       __________________________________________________________________________            Testing    Polypro-                                                                           Polypro-                                                                           Polypro-                                                                           Polypro-                                                                           Polypro-                                                                           Polypro-                          Item    Method                                                                             Unit  pylene A                                                                           pylene B                                                                           pylene C                                                                           pylene D                                                                           pylene E                                                                           pylene F                          __________________________________________________________________________    Characteristics                                                               MFR     JISK6758                                                                           g/10  10.1 12.3 16.6 24.4 8.0  12.0                                           min.                                                             Bending JISK7203                                                                           kg/cm.sup.2                                                                         15000                                                                              15000                                                                              19000                                                                              18000                                                                              19000                                                                              12000                             Elasticity                                                                    Bending JISK7203                                                                           kg/cm.sup.2                                                                         410  460  520  500  --   410                               Strength                                                                      Izod (23° C.)                                                                  JISK7110                                                                           kg-cm/cm                                                                            5.1  4.3  3.0  4.0  2.2  4.5                               Thermo- JISK7207                                                                           °C.                                                                          114  114  126  125  125  114                               deforming                                                                     Temperature                                                                   Drop Test                                                                     Sample Numbers     10   10   10   10   10   10                                Contents Leaked Numbers                                                                          0    2    7    2    3    0                                 Good Product       10   8    3    8    7    10                                Result             ⊚                                                                   Δ                                                                            X    Δ                                                                            Δ                                                                            ⊚                  __________________________________________________________________________     where MFR: Melt Flow Rate                                                

The respective containers 10 provided with metallic covers utilized forthese tests each provided with a bottom edge portion having a diameterof 61 mm, a height of 54 mm and an inner volume of 150 ml.

As is clear from the table, good results of the dropping down testscould be obtained with respect to the polypropylenes of the types A andF and no content leaked. On the other hand, with respect to thepolypropylenes of the types B, C, D and E, the bottom edge portions 29of some of containers 10 with the metallic covers were damaged and partsof the contents leaked.

From the above, it was found that, containers formed of some of thepolypropylenes of the types A to F, which have MFR values less than 12g/10 min., bending elasticity ratio more than 12,000 kg/cm² and Izodimpact value more than 4.5 kg-cm/cm were not damaged at the bottom edgeportions 29 and the contents did not leak.

Although the dropping tests were performed for the containers formed ofthe polypropylenes, it will be foreseen that substantially the sameresults will be obtained even in a case where the drop tests be carriedout to the containers formed of another thermally fusible resin whichhas substantially the same physical property as that described above.

(1-3-4 Effects)

According to this invention, the strength of the bottom edge portion ofthe container body 14 can be improved and the bottom edge portion 29 ofthe containers can be prevented from being damaged when dropped. Forthis reason, a container provided with a metallic cover which is freefrom contents leakage can be obtained.

§2. Second Embodiment of Container provided with Metallic Cover(Container having a container body formed of a laminated layer subjectedto sheet forming treatment)

(2-1-1 Basic Structure)

FIGS. 16 to 19 show a container provided with a metallic cover having aflanged portion having a substantially entirely uniform thickness.

A container body of the container provided with the metallic coveraccording to this invention will be first described hereunder withreference to FIG. 16. Referring to FIG. 16, the container body 14 isentirely formed of a plastic material and comprises a shell portion 14aprovided with an upper end opened, a bottom portion 14b and a flangedportion 15 disposed at the peripheral edge of the opening of the shellportion 14a and extends radially outward therefrom.

The flanged portion 15 of the container body 14 has substantially thesame thickness t from the base end 15a to the front end 15b.

The container body 14 of the character described above is filled with acontent 19 of high temperature and the peripheral edge portion 12 of themetallic cover 11 is roll-seamed to the flanged portion to thereby forma container 10 provided with a metallic cover (refer to FIG. 8).

(2-1-2 Manufacturing Method)

A manufacturing method for the container provided with the metalliccover of the type described above will be described hereunder.

Reference should be first made to FIG. 19, through which thermoformingprocesses due to a general sheet forming process for manufacturing aproduct of a container body are explained.

A plastic sheet 50 having a thickness adequate for forming a containeris first heated by a heating device. 61 and a product 40 including aplurality of container bodies 14 is molded by a usually known moldingmethod by means of a mold 62. A pressure forming or vacuum forming, or acombination thereof may be utilized for this molding method.

Each of the container bodies 14 of the mold product 40 is provided witha shell portion 14a has a thickness and strength sufficient forwithstanding the pressure applied thereto during the double seamingprocess. However, the flanged portion 15 thus formed has a largethickness which is not applicable for the double seaming process, andaccordingly, a further pressing process is required for the formation ofthe flanged portion 15.

It is desired for the plastic sheet 50 for forming the container body 14to be formed of a plastic laminated material having a less permeabilitywith respect to an oxygen gas and water vapor in order to preserve foodin the container. It is therefore desired for food preserving containersthat the oxygen gas barrier property be less than 0.8 cc/one article; 24hrs. atm. (20° C., 90% RH) and the H₂ O gas barrier property is lessthan 0.2 g/one article; 24 hrs. atm. (40° C., 90% RH).

In the subsequent steps, a plurality of container bodies 14 constitutingthe mold product 40 are separated respectively. The thickness of theflanged portion 15 is reduced by the pressing process and the width ofthe flanged portion 15 is cut so as to have a predetermined width by acutting process to thereby obtain a container body 14 such as shown inFIG. 16.

The pressing and cutting processes of the flanged portion 15 will bedescribed hereunder with reference to FIGS. 17 and 18.

Referring to FIG. 17, a pressing device for carrying out the pressingprocess comprises a press male mold half 41 in which the plasticcontainer body 14 is mounted in an inversed state and a press femalemold half 43 arranged above the press male mold half 41 to be verticallymovable.

The press male mold half 41 is provided with an abutting surface 42which abuts against the upper surface of the flanged portion 15 of thecontainer body 14 and the press female mold half 43 is also providedwith an abutting surface which abuts against the lower surface of theflanged portion 15. A heating heater 45 is wound around the outerperiphery of the press male mold half 41 to heat the same and a heatingheater 46 is likely wound around the outer periphery of the press femalemold half 43 to heat the same.

The gap between the abutting surfaces 42 and 44 of the male and femalemold halves 41 and 43 has a width substantially equal to the distancebetween the base end 15a and the front end 15b of the flanged portion15.

The pressing process is carried out as follows.

A guide member 49 having an outer shape corresponding to the inner shapeof the container body 14 separated from the mold product 40 is insertedinto the container body 14 and then mounted on the press male mold half41 with the flanged portion 15 downward. The press female mold half 43is then lowered so as to snap and press, while heating, the flangedportion 15 between the abutting surfaces 42 and 44 of the mold halves 41and 43 to thereby form the flanged portion 15 having a predeterminedthickness. The press female mold half 43 may be actuated by hydraulic orpneumatic assembly.

When the thickness of the flanged portion has reached to thepredetermined value, the press female mold half 43 is elevated, wherebythe pressing process for forming the flanged portion 15 having a reducedthickness has been completed.

In accordance with this pressing process, the thickness of the flangedportion 15 is reduced to the predetermined value t substantiallyuniformly from the base end 15a to the front end 15b thereof. It may bedesired for the flanged portion 15 to have a thickness t of 0.25 to 0.9mm. It is also desired that the thickness t of the flanged portion 15 iswithin the range of 0.9 t₀ ≧t₁ ≧0.4 t₀ and, preferably, 0.9 t₀ ≧t₁ ≧0.6t₀, where t₀ is an original thickness of the flanged portion 15 and t₁is a thickness after pressed. Namely, in the range of t₁ ≧0.9 t₀, thethickness of the flanged portion 15 is too large to sufficientlycompensate for the unevenness of the thickness and to carry out adesired double seaming process.

In the range of t₁ ≦0.4 t₀, the flanged portion 15 is excessivelycrushed, so that a relatively large volume of plastic material forforming the flanged portion 15 will be extruded. For this reason, aseries of lumps may be formed around the pressed portion or the flangedportion 15 may be thermally deformed and, hence, the flanged portion 15having a uniform thickness will not be formed.

Since the guide member 49 is inserted into the container body 14 duringthe pressing process, the stable positioning of the container body 14will be achieved and the pressing process can thus be performed withhigh accuracy. The formation of a series of lumps in the container body14 can be prevented, so that the shape of the flanged portion is notdeformed.

The container body 14 is thereafter cooled for the predetermined timeand the flanged portion 15 is cut by means of the cutting device asshown in FIG. 18 so as to have a predetermined width.

The cutting device comprises a cut male half 56 and a cylindrical cutfemale half 58 disposed above the cut male half 56 to be verticallymovable.

A guide member 57 having an outer shape corresponding to an inner shapeof the container body 14, is inserted into the container body 14 and thecontainer body 14 is arranged on the cut male half 56 with the flangedportion downward. During this process, the container body 14 is vacuumsecured to the guide member 57 by means of a vacuuming passage 57aformed in the guide member 57a.

The cut female half 58 is thereafter lowered to punch out the flangedportion 15 in engagement with the peripheral portion of the cut malehalf 56 to form the flanged portion 15 having a predetermined width.

Since the guide member 57 is inserted during the cutting process, thecontainer body 14 is stably positioned on the cut male half 56 and theflanged portion 15 is therefore cut with high accuracy.

Highly heated contents 19 be accommodated in the thus formed containerbody 14. The peripheral portion 12 of the metallic cover 11 is rollseamed to the flanged portion 15 of the container body, thus forming thecontainer 10 provided with the metallic cover (FIG. 8).

When the flanged portion 15 is roll seamed with the peripheral edge 12of the metallic cover 11, since the thickness t of the flanged portion15 is made substantially uniform from the base end 15a to the front end15b, the softening of the base end 15a of the flanged portion 15 due tothe highly heated content 19 is minimized in comparison with the flangedportion having a thickness less than t. Therefore, the seaming processcan be effectively performed with a uniform and sufficient seamingstrength entirely throughout the base end 15a and the front end 15b.

(2-1-3 Effects)

According to this invention, the peripheral edge 12 of the metalliccover 11 can be seamed to the flanged portion 15 of the container body14 in a uniformly and safely sealed manner throughout the base end 15aand the front end 15b of the flanged portion 15 even if the container isfilled with highly heated contents. Accordingly, a container providedwith a metallic cover which is free from the leakage of the contents canbe provided.

2.2 Container provided with a metallic cover having a container bodyformed by a laminated material including ethylene vinyl alcoholcopolymer containing a drying agent

(2-2-1 Basic Structure)

FIGS. 20 to 22 show a container provided with a metallic cover having acontainer body formed by a laminated material including ethylene vinylalcohol copolymer containing a drying agent.

The container 10 provided with the metallic cover is formed by rollseaming the peripheral portion 12 of the metallic cover 11 made of suchas aluminum or tin plate metal to the flanged portion 15 of the plasticcontainer body 14 (see FIG. 8).

(2-2-2 Manufacturing Method)

The manufacturing method of the plastic container body 14 will bedescribed hereunder with reference to FIGS. 20 to 22.

A laminated material 50 of plastics having a thickness necessary for theformation of the container due to a general thermoforming method isheated by means of a heating device 61 and a mold product 60 is moldedby a generally known forming method by means of a mold 62. A pressureforming method or a vacuum forming method, or a combination methodthereof may be utilized for the forming method (process A).

The plastic laminated material 50 for forming the container body 14 hasa less permeability to the oxygen gas and the water vapor when thecontainer is manufactured for the preservation of foods.

The followings may be listed up as a layer structure for the laminatedmaterial 50.

Polypropylene/bonded layer/ethylene vinyl alcohol copolymer(EVOH)/bonded layer/polypropylene; and

Polystyrene/bonded layer/ethylene vinyl alcohol copolymer (EVOH)/bondedlayer/polystyrene.

A drying agent such as CaCl₂, CaO, NaCl, or Na₄ PO₄ is preliminarilymixed in the EVOH layer of the lamination structure described above.Namely, the drying agent may be mixed in a time when the laminatedmaterial 50 is formed during the co-extrusion process.

The product 40 formed by the process A is not adopted as a mold productbecause of the flanged portion having a large thickness is not suitablefor the double seaming process. For this reason, the flanged portion 15is subjected to the heat pressing process to reduce the thicknessthereof for improving the molding process.

Namely, the molded container body 14 is inserted into the cavity 69 asshown in FIG. 21, which is heated and the surface of which is processedby the surface treatment by utilizing such as Teflon for improving themold removability. A heated plug means 70 is then lowered from the upperportion to crush the flanged portion 15 (FIG. 21). The plug means 70 maybe actuated by hydraulic means or pneumatic means. When the thickness ofthe flanged portion 15 has reached to the predetermined value, the plugmeans 70 is elevated and the flange crushing process has thus beencompleted (process B).

The product 40 provided with the flanged portion having thepredetermined thickness through the process B is then punched out bymeans of a plug 74 provided with a cutter 73 so that the flanged portion15 has a predetermined width (process C).

The container body 14 is manufactured in accordance with the processesdescribed above. The container body 14 is then filled with a content 19and the peripheral, portion 12 of the metallic cover 11 is roll seamedto the flanged portion 15 of the container body 14 to thereby produce acontainer provided with a metallic cover (see FIG. 8).

According to this embodiment, since the drying agent is preliminarilymixed in the EVOH layer of the lamination structure of the laminatedmaterial 50 forming the container body 14, the water content mixed inthe EVOH layer can be surely removed, whereby the lowering of thegas-barrier property of the EVOH layer due to the presence of the watercontent can be effectively prevented.

(2-2-3 Effects)

According to this invention, since the drying agent is preliminarilymixed in the ethylene vinyl alcohol copolymer layer of the laminationstructure forming the plastic container body 14, the lowering of thegas-barrier property of the ethylene vinyl alcohol copolymer layer canbe surely prevented and, therefore, the reservation and maintenanceabilities of the container 10 provided with the metallic cover can beremarkably improved.

2.3 Container provided with a metallic cover having a container bodyprovided with a flanged portion having a lower base end in which anannular recess is formed

(2-3-1 Basic Structure)

FIGS. 23 to 26 show a container provided with a metallic cover having acontainer body provided with a flanged portion having a lower base endin which an annular recess is formed and FIG. 24 is an enlarged view ofthe portion A shown in FIG. 23 and FIG. 25 is also an enlarged view ofthe portion B shown in FIG. 24.

A container body according to this invention will first be explainedwith reference to FIG. 26. Referring to FIG. 26, the container body 14is composed of a shell portion 14a provided with an upper end opened, abottom portion 14b, and a flanged portion 15 formed at the upper endopening of the shell portion 14a and extending radially outwardlytherefrom. The container body 14 is entirely made of a plastic material.

The flanged portion 15 is provided with an upper surface 75a and a lowersurface. 75b, which has a base end in which an annular recess 76extending in a circumferential direction is formed.

A container 10 provided with a metallic cover is formed by roll seamingthe peripheral portion 12 of the metallic cover 11 to the flangedportion 15 of the container body 14 of the construction described above(see FIG. 8).

With the container of this character, since the annular recess 76 isformed in the base end of the lower surface 75b of the flanged portion15 so as to extend in the circumferential direction, the flanged portion15 is pliably bent at this annular recess 76, whereby the peripheralportion 12 of the metallic cover 11 can be more easily roll seamed tothe flanged portion 15 of the container body 14.

(2-3-2 Manufacturing Method)

The manufacturing method of the plastic container body of the structuredescribed above will be explained hereunder.

As shown in FIG. 22 with respect to the container provided with themetallic cover described in section 2.2, processes for manufacturing amold product of the container body by a thermoforming treatment due to ageneral sheet forming process will be described hereunder.

A plastic sheet 50 having a thickness adequate for forming a containeris first heated by a heating device 61 and a product 40 including aplurality of container bodies 14 is molded by a usually known moldingmethod by means of a mold 62. A pressure forming or vacuum forming, or acombination thereof may be utilized for this molding method

Each of the container bodies 14 of the mold product 40 is provided witha shell portion 14a has a thickness and strength sufficient forwithstanding the pressure applied thereto at the double seaming process.However, a flanged portion 15 thus formed has a large thickness which isnot applicable for the double seaming process, and accordingly, afurther pressing process is required for the formation of the flangedportion 15.

It is desired for the plastic sheet 50 for forming the container body 14to be formed of a plastic laminated material having a lower permeabilitywith respect to an oxygen gas and water vapor in order to preserve foodin the container. It is therefore desired for food preserving containersthat the oxygen gas barrier property of the container be less than 0.8cc/100 cc; 24 hrs. atm. (20° C., 90% RH) and the H₂ O gas barrierproperty is less than 0.2 g/100 cc; 24 hrs. atm. (40° C. 90% RH)

In the subsequent steps, a plurality of container bodies 14 constitutingthe mold product 40 are separated respectively. The thickness of theflanged portion 15 is reduced by the pressing process and the width ofthe flanged portion 15 is cut so as to have a predetermined width by acutting process to thereby obtain a container body 14 such as shown inFIG. 26.

The pressing and cutting processes of the flanged portion 15 will bedescribed hereunder with reference to FIGS. 23 and 25.

Referring to FIGS. 23 to 25, a pressing device for carrying out thepressing process comprises a press male mold half 41 in which theplastic container body 14 is mounted in an inversed state and a pressfemale mold half 43 arranged above the press male mold half 41 to bevertically movable.

The press male mold half 41 is provided with an abutting surface 42which abuts against the upper surface 75a of the flanged portion 15 ofthe container body 14 and the press female mold half 43 is also providedwith an abutting surface 44 which abuts against the lower surface 75b ofthe flanged portion 15. A heating heater 45 is wound around the outerperiphery of the press male mold half 41 to heat the same and a heatingheater 46 is likely wound around the outer periphery of the press femalemold half 43 to heat the same.

An annular projection 47 extending in the circumferential direction isformed inside the abutting surface 44 of the press female mold half 43.

The annular projection 47 will be described in detail in conjunctionwith FIG. 25.

The annular projection 47 has a semicircular cross section. A curvedsurface 48 is formed on the abutting surface 42 of the press male moldhalf 41 to correspond to the shape of the annular projection 47. Thecurved surface 48 has a radius seven or eight times the radius of theannular projection 47.

The annular recess 76 is formed at the base end of the lower surface 75bof the flanged portion of the container body so as to extend in thecircumferential, direction thereof in combination of the annularprojection 47 and the curved surface 48.

The distance between the abutting surface 42 and the abutting surface 44is widened outwardly (leftwardly as viewed in FIG. 25). For this reason,an extra portion of the flange forming portion is extruded outwardlyduring the pressing process, whereby a series of lumps is never formedand the pressing process can be performed with an improved accuracy.

The pressing process is carried out as follows.

A guide member 49 having an outer shape corresponding to the inner shapeof the container body 14 separated from the mold product 40 is insertedinto the container body 14 and then mounted on the press male mold half41 with the flanged portion 15 downward. The press female mold half 43is then lowered so as to snap and press, while heating, the flangedportion 15 between the abutting surfaces 42 and 44 of the mold halves 41and 43 to thereby form the flanged portion 15 having a predeterminedthickness. The press female mold half 43 may be actuated by hydraulic orpneumatic means.

When the thickness of the flanged portion has reached to thepredetermined value, the press female mold half 43 is elevated, wherebythe crushing process for forming the flanged portion 15 has beencompleted.

In accordance with this pressing process, the, thickness of the flangedportion 15 is reduced to the predetermined value and the annular recess76 extending in the circumferential direction is formed in the base endof the lower surface 75a of the flanged portion 15. It may be desiredfor the flanged portion 15 to have a thickness t of 0.25 to 0.9 mm. Itis also desired that the thickness t of the flanged portion 15 is withinthe range of 0.9 t₀ ≧t₁ 0.4 t₀ and, preferably, 0.9 t₀ ≧t₁ 0.6 t₀, wheret₀ is an original thickness of the flanged portion and t₁ is a thicknessafter the pressing. Namely, in the range of t₁ ≧0.9 t₀, the thickness ofthe flanged portion 15 is too large to sufficiently compensate for theunevenness of the thickness and to carry out a desired double seamingprocess.

In the range of t₁ ≦0.4 t₀, the flanged portion 15 is excessivelycrushed, so that a relatively large volume of plastic material forforming the flanged portion 15 will be extruded. For this reason, aseries of lumps may be formed around the pressed portion or the flangedportion 15 may be thermally deformed and, hence, the flanged portion 15having a uniform thickness will not be formed.

Since the guide member 49 is inserted into the container body 14 duringthe pressing process, the stable positioning of the container body 14will be achieved and the pressing process can thus be performed withhigh accuracy. The formation of a series of lumps in the container body14 can be prevented, so that the shape of the flanged portion never bedeformed.

The container body 14 is thereafter cooled for the predetermined timeand, thereafter, the flanged portion 15 is cut by means of the cuttingdevice as shown in FIG. 18 and described with respect to the containerprovided with the metallic cover of 2.1 so as to have a predeterminedwidth.

As shown in FIG. 18, the cutting device comprises a cut male half 56 anda cylindrical cut female half 58 disposed above the cut male half 56 tobe vertically movable.

A guide member 57 having an outer shape corresponding to an inner shapeof the container body 14 is inserted into the container body 14 and thecontainer body 14 is arranged on the cut male half 56 with the flangedportion downward. During this process, the container body 14 is vacuumsecured to the guide member 57 by means of a vacuuming passage 57aformed in the guide member 57.

The cut female half 58 is thereafter lowered to punch out the flangedportion 15 in engagement with the peripheral portion of the cut malehalf 56 to form the flanged portion 15 having a predetermined width. Itis desired for the flanged portion 15 to have a width having a thicknessof about 1.0 to 2.5 mm.

Since the guide member 57 is inserted during the cutting process, thecontainer body 14 is stably positioned on the cut male half 56 and theflanged portion 15 is therefore cut with high accuracy.

With the embodiment described above, it may be possible to arrange acooling pipe inside the guide member 49 of the pressing device and theguide member 57 of the cutting device to cool the guide members. In suchcase, the transferring of the heat to the container body 14 during thepressing and cutting processes can be effectively prevented, whereby thedeformation of the container body 14 can also be surely prevented.

(2-3-3 Effects)

According to this invention, since the circumferentially extendingannular recess 76 is formed in the base end of the lower surface 75b ofthe flanged portion 15, the flanged portion 15 is liably easily bent atthis recessed portion 76, whereby the peripheral portion 12 of themetallic cover 11 can be easily seamed to the flanged portion of thecontainer body 14. In addition, since the circumferentially extendingannular projection 47 is formed inside the abutting surface 44 of thepress female mold half 43 of the pressing device, the annular recess 76can be easily formed to the base end of the lower surface of the flangedportion 15 during the pressing process.

§3. Third Embodiment of Container provided with Metallic Cover(Container provided with a sealing member disposed at a seaming portion)

3.1 Container provided with a metallic cover having a heat sealingmember as a sealing member

(3-1-1 Basic Structure)

FIGS. 27 to 29 show a container provided with a metallic cover having aheat sealing member as a sealing member for the container, wherein FIG.27 shows a container before seaming, FIG. 28 shows the container afterthe seaming and FIG. 29 is an enlarged view of a portion C in FIG. 28,

The container 10 provided with the metallic cover is composed of aplastic container body 14 having a flanged portion 15 formed around theupper end opening of a shell portion 14a and a metallic cover 11 havinga peripheral edge 12 which is roll seamed to the flanged portion 15. Themetallic cover 11 is composed of a cover body 11a for sealing theopening of the container body 14 and a shoulder portion 13 formedbetween the cover body and the peripheral edge 12.

A heat sealing member 87 is disposed near the shoulder portion 13 and ispositioned between the peripheral edge 12 of the metallic cover 11 andthe flanged portion 15 of the container body 15 when the cover issealed.

The metallic cover 11 according to this embodiment is made of a tinplatemetal or aluminum metal.

The plastic container body 14 is not limited in the material and may beformed of a material having a hardness and strength sufficient forwithstanding the roll seaming force and a laminated material mainlycomposed of olefine type resin and polypropylene will be preferablyutilized. The flanged portion 15 of the container body 14 has athickness of 0.2 to 1.0 mm and a width of 1.0 to 2.5 mm.

The heat sealing member 87 disposed between the flanged portion 15 andthe peripheral edge 12 of the cover 11 is mainly composed of a denaturedpolyolefine resin, ionomer resin, ethylene-acrylic acid copolymer, orthe like and, particularly, a denatured polyolefine resin may bepreferred.

As the polyolefine, is used a sole polymer of α-olefin such as ethyleneor propylene, or a copolymer with another olefine such as crystallisticcopolymer of α-olefin such as ethylene-propylene random copolymer,ethylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, orthe combination of these polymers. The denaturing of the polyolefinewill be performed by effecting the graft polymerization of anunsaturated carboxylic acid or anhydride to the polyolefine of the typedescribed above. Acrylic acid, maleic acid, fumaric acid, itaconic acid,crotonic acid, citraconic acid, or sorbic acid may be utilized as theunsaturated carboxylic acid and an anhydride of these acids may beutilized as the anhydride. Particularly, acrylic acid or anhydridemaleic acid may be preferred.

The ratio of a reformed monomer in the denatured polyolefine withrespect to the denatured polyolefine will be preferred in a range of0.01 to 1 wt. % with respect to the contained olefine amount(undenatured polyolefine+deformed polyolefine).

These denatured polyolefine are materials easily fusible and thermallyfused to the plastic container 14 (olefine type resin) and, in addition,provide a good bonded condition to the metallic cover 11.

(3-1-2 Manufacturing Method)

The manufacturing method of the container 10 provided with the metalliccover of the structure described above will be explained hereunder.

The heat sealing member 87 such as a denatured polyolefine is firstcoated on the inner surface of the peripheral edge 12 of the metalliccover 11 at a radially inward portion thereof (near the shoulder portion13) and, in other words, at a portion near the shell portion 14a of thecontainer body 14 when the peripheral edge 12 of the metallic cover 11is seamed to the flanged portion 15 of the container body 14.

The denatured polyolefine is dissolved and sprayed to coat the same andis formed to a colloid under the presence of water or solvent in form ofa dispersion and then coated. The amount of the coating is about 3 to 4mg/cm².

A content 19 is packaged in the container body 14 and the peripheralportion 12 of the metallic cover 11 is roll seamed to the flangedportion 15 of the container body 14. This roll seaming operation can bedone by pressing the container 10 provided with the metallic cover 11and the container body 14 upwardly and downwardly in the verticaldirection and pressing the required portion by a seaming roll.

When the container body 14 and the metallic cover 11 are pressedvertically, since the denatured polyolefine is coated radially inwardlyof the peripheral edge 12, the flanged portion 15 can be easily securedto the peripheral portion 12 of the metallic cover 11 in comparison witha case where the denatured polyolefine is coated radilly outwardly.

In the next step, the thus seamed portion 89 is heated by means of ahigh-frequency welder, not shown, to thereby surely fuse the peripheraledge 12 of the metallic cover 11 to the flanged portion 15 of thecontainer body 14 in the presence of the denatured polyolefine formed asthe heat sealing member 87.

According to this embodiment, the heat sealing member 87 is disposed ata portion near the shell portion 14a of the container body 14, so thatthe sealing performance of the seamed portion 89 of the container body14 can be remarkably improved. Namely, in a case where the flangedportion 15 and the peripheral portion 12 of the metallic cover 11 areseamed by applying the pressing force in a direction outward to theportion to be seamed, both the portions are tightly contacted to eachother at the outer side of the portion to be seamed, but a gap is liablyformed at the inner side thereof. The smaller the roll seaming force,the wider the gap. For this reason, the sealing performance of theseamed portion 89 can be improved by disposing the heat sealing member87 at a portion near the shell portion 14a of the container body 14,i.e. the shoulder portion 13 of the metallic cover 11.

Although, in the described embodiment, the denatured polyolefine is usedas the heat sealing member, a conventional rubber type heat sealingmember may be also utilized for this invention.

(3-1-3 Effects)

According to this invention, a portion to be seamed as the seamedportion 89 near the shell portion 14a can be sealed by the heat sealingmember 87, so that the packaged contents 19 never leak from thecontainer.

3.2 Container provided with a metallic cover having a rubber typesealing member as a sealing member

(3-2-1 Basic Structure)

FIGS. 30 to 34 show a container provided with a metallic cover having asealing member formed of a rubber type sealing member.

Referring to FIG. 31, a container 10 provided with a metallic cover isconstructed by seaming a peripheral portion 12 of the metallic cover 11having front and rear surfaces 91 and 92 coated to a flanged portion ofa plastic container body 14 in which a content 19 is packaged. A sealingcompound 3 is annularly coated to the portion to be seamed between theperipheral portion 12 of the metallic cover 11 and the flanged portion15 of the container body 14 to effect the sealing of that portion.

The container 10 provided with the metallic cover according to thisembodiment will be described in detail hereunder with reference to FIG.30 which shows the container body 14 and the metallic cover 11 beforethe roll seaming operation.

The container body 14 is provided with the flanged portion 15 made of aplastic material and formed around the upper opening thereof. Thematerial constituting the container body 14 is not limited to theplastic material and other material having a hardness and strengthsufficient for withstanding the roll seaming force such as a laminatedmaterial mainly composed of an olefine type resin or polypropylene maybe utilized.

The metallic cover 11 comprises a cover body 11a and the peripheralportion 12 connected to the cover body 11a through a shoulder portion 13and the peripheral edge 12 is roll seamed to the flanged portion 15 ofthe container body 14.

The metallic cover 11 is prepared, as shown in FIG. 32, by coating thefront and rear surfaces of the aluminum metallic sheet 90 (having athickness of 0.30 mm) as a front coat 91 and a rear coat 92 andpress-forming the thus coated metallic sheet 90, thus forming themetallic cover 11 of the shape shown in FIG. 33.

An epoxy acrylate having a thickness of 0.03 mm, for example, isutilized for the front coat 91 and an epoxy phenol having a thickness of0.05 mm, for example, is utilized for the rear coat 92. Namely, themetallic cover 11 is of the layer structure of epoxy acrylate (0.03mm)/aluminum sheet (0.25 mm)epoxy phenol (0.005 mm).

The epoxy acrylate layer is formed for improving the outer brillianceand corrosion proof property of the metallic cover 11.

The sealing compound 93 is coated, as shown in FIG. 30, before theseaming operation, on substantially the entire inner surface area(substantially entire area directed from the radially inside to theoutside) of the peripheral portion 12 of the metallic cover 11.

The sealing compound 93 is formed of a rubber type material andcompressed at the seaming of the peripheral portion 12 of the metalliccover 11 to the flanged portion 15, whereby the sealing compound 93buries the portion to be seamed between the peripheral portion 12 of themetallic cover 11 and the flanged portion 15 to effect the seal.

According to the described embodiment, since substantially the entireinner surface of the peripheral portion 12 of the metallic cover 11 iscoated with the sealing compound 93, the seamed portion between theperipheral portion 12 of the metallic cover 11 and the flanged portion15 of the container body 14 can be surely sealed.

(3-2-2 Concrete Example)

As shown in FIGS. 34(a) to 34(e), tests for the reservation performancewere performed by variously changing coating conditions of the sealingcompound 93. Details of The Sealing Compound Used

i. Name: Dalex, Can, Sealing Compound SLC-235 (Grace Japan KABUSHIKIKAISHA)

ii. Material: Mainly Composed of Butyl Rubber and Containing HexaneSolution

iii. Standard: Solid Component 42.0±2% Dry Density 1.23±0.03 ViscosityBH Viscosity 4000±1000 Cps (20° C., Rotor 4, 20 rpm)

Reservation Test Carried out

A suspected content filled in the container 10 provided with a metalliccover and was treated in a retort (120° C.: 30 min.). Thereafter, thecontainer 10 was kept for two weeks in a constant temperature room (37°C.) and the swelling condition of the container 10 and the leakage ofthe content 19 has been observed for these two weeks.

The results of these reservation tests are summarized in the followingTable.

                  TABLE                                                           ______________________________________                                               Corre-                Coating                                                                              Test Result                               Ex-    sponding              Amount (Faulty                                   ample  FIG.     Coated Position                                                                            (mg)   Product)                                  ______________________________________                                        A      FIG.     Entire Area of                                                                             60     0/200                                            34(a)    Peripheral Edge                                               B      FIG.     Near Shoulder                                                                              60     0/200                                            34(b)    Portion of                                                                    Peripheral Edge                                               C      FIG.     Near Front End                                                                             60     6/200                                            34(c)    of Peripheral                                                                 Edge                                                          D      FIG.     Shoulder Portion                                                                           62     9/200                                            34(d)                                                                  E      FIG.     No coating    0     2/200                                            34(e)    Entire Area of                                                                Peripheral Edge                                               F      FIG.     No coating   40     1/200                                            34(a)    Entire Area of                                                                Peripheral Edge                                               G      FIG.     No coating   50     0/200                                            34(a)    Entire Area of                                                                Peripheral Edge                                               H      FIG.     No coating   100    0/200                                            34(a)    Entire Area of                                                                Peripheral Edge                                               I      FIG.     No coating   120    4/200                                            34(a)    Entire Area of                                                                Peripheral Edge                                               ______________________________________                                    

As is clear from the above Table, with the examples A and B in which thesealing compound 93 of 60 mg was coated to substantially the entire areain the peripheral portion 12 of the metallic cover 11 from the radiallyinside portion to the outside portion and a portion near the shoulderportion 13, the reservation test showed good results. These results areconsidered good for the reason that, in the seamed portion between theperipheral portion 12 of the metallic cover 11 and the flanged portion15 of the container body 14, a gap is liably formed radially inside,i.e. shoulder portion side, and the gap is buried by the sealingcompound 93 by coating the compound at least to a portion near theshoulder portion 13 of the inner surface of the peripheral edge portion12.

Accordingly, with the example C in which the sealing compound 93 iscoated at a portion near the front end of the peripheral portion 12 ofthe metallic cover 11, the reservation test showed no good result. Withthe example D in which the sealing compound 93 is coated only to theshoulder portion 13 which is not directly concerned with the seamingoperation, the reservation test showed also no good result.

With the examples A, F, G, H and I in which, as shown in FIG. 34(a), thesealing compound 93 was coated to substantially entire area of theperipheral portion 12 of the metallic cover 11 and the coating amountwas changed, the reservation tests showed good results in a case wherethe coating amount is more than 50 mg and less than 100 mg. In case ofless than 50 mg, the amount of the sealing compound is too small toachieve the desired seaming effect and in case of more than 100 mg, theamount of the sealing compound is too large to attain the desiredseaming function.

(3-2-3 Effects)

According to this invention, the sealing compound 93 is coated to atleast a portion near the shoulder portion 13 in the portion to be seamedbetween the peripheral edge portion 12 of the metallic cover 11 and theflanged portion 15 of the container body 14, so that the seamed portioncan be surely sealed. Accordingly, a container provided with a metalliccover superior in the reservation performance of the content can beobtained.

§4. Fourth Embodiment of Container Provided with Metallic Cover

4.1 Container provide with a metallic cover having a portion to beseamed having a seaming width of a specific shape

(4-1-1 Basic Structure)

FIGS. 35 and 36 show a container provided with a metallic cover having aseamed portion having a seaming width of a specific shape and FIG. 36 isan enlarged view of a portion D in FIG. 35.

Referring to FIG. 35, the container 10 provided with the metallic covercomprises a plastic container body 14 provided with a flanged portion 15and a metallic cover 11 provided with a peripheral edge portion 12 whichis double seamed to the flanged portion.

As shown in FIG. 36, the entire inner surface of the metallic cover 11is preliminarily coated with a laminated material 106 of an epoxy typeresin and a denatured polyolefine. The laminated material 106 serves tobury the gap between the peripheral portion 12 of the metallic cover 11and the flanged portion 15 of the container body 14 by effecting a heattreatment to the seamed portion 103 after the seaming operation.

The plastic container body 14 utilized in this embodiment is not limitedin the material and may be formed of a material having a hardness andstrength sufficient for withstanding the roll seaming force and alaminated material mainly composed of olefine type resin andpolypropylene will be preferably utilized. It is preferred that theflanged portion 15 of the container body 14 has a thickness of 0.2 to1.0 mm and a width of 1.0 to 2.5 mm.

The details of the seamed portion 13 of the peripheral portion 12 of themetallic cover 11 and the flanged portion 15 of the container body 14will described hereunder with reference to FIG. 36.

The seamed width W of the seamed portion 103 is ranged as follows.

    0.5(3M+2P)≦W<3M+2P                                  (1)

In the equation (1), M designates a thickness of the peripheral portion12 of the metallic cover 11 before the seaming and P is a thickness ofthe flanged portion 15 of the container body 14 before the seaming.

The overlapped length OL in a height direction of the seamed portion 103between the end of the flanged portion 15 and the end of the peripheralportion 12 is represented as follows.

    OL≧0.055L                                           (2)

where L designates an inner height of the seamed portion 103 and aletter T in FIG. 36 designates an outer height of the seamed portion103.

(4-1-2 Manufacturing Method)

A manufacturing method of a container provided with a metallic cover ofthe structure described above will be briefly described hereunder.

A content 19 is first packaged in the container body 14 and the metalliccover 11 is loosely applied to the container body 14 under a state thatthe peripheral portion 12 of the metallic cover 11 is overlapped withthe flanged portion 15 of the container body 14 and the peripheralportion 12 is thereafter double seamed to the flanged portion 15. Thisdouble seaming operation is performed by vertically pressing thecontainer 10 provided with the metallic cover with the peripheralportion 12 and the flanged portion 15 loosely engaged and pressing fromthe outer side the overlapped portion of the peripheral portion 12 andthe flanged portion 15 by means of a seaming roll, not shown. Theflanged portion 15 and the peripheral portion 12 are tightly doubleseamed by this seaming operation.

The seamed portion 103 formed by the double seaming operation describedhas a suitable shape based on the former equations (1) and (2).

Namely, in a case where the seamed width W of the seamed portion 103 isover (3M+2P), it is difficult to keep an adequate sealing function andin a case where the width W is below 0.5×(3M+2P), the peripheral portion12 and the flanged portion 15 may be largely pressed and, in an adversecase, the flanged portion 15 may be damaged.

Generally, it is said for the seaming operation of the metallic coverand the container body that it is needed for the seamed portion to havean overlapped length more than (seamed height)×0.4. However, accordingto this invention, as shown in the equation (2), the overlapped lengthOL of the seamed portion 103 is more than (inner height of the seamedportion 103)×0.05 (5%). This is because of the container body 14 beingformed of the plastic material which is flexible and superior in thesealing function. For this reason, the width of the peripheral portion12 and the width of the flanged portion to be double seamed are madeshort in comparison with a case where a metallic cover is seamed to ametallic container body.

The peripheral portion 12 after seamed is heat treated by a highfrequency welder, for example, not shown, to fuse the laminated material106 to thereby bury the gap between the peripheral portion 12 and theflanged portion 15.

According to this embodiment, a container 10 provided with a metalliccover having an improved sealing function can be obtained by performinga double seaming operation.

In the foregoing embodiment, the laminated material 106 may beeliminated as occasion demands.

(4-1-3 Specific Example)

Specific examples according to this embodiment will be describedhereunder.

A container body 14 was formed by vacuum forming a laminated material ofthe structure having polyethylene/ethylene vinyl alcoholcopolymer/polyethylene (diameter of opening: 65.3 mm; depth: 35 mm;thickness of a flanged portion: 0.3 mm). Water was filled in the thusformed container body 14 and an aluminum metallic cover 11 (thickness:0.27 mm) was seamed to the container body 14 by means of a semitronseamer. Leakage tests were carried out for the containers thus formedhaving various seamed widths and overlapped lengths and the results ofthe tests are shown in the following Table.

                  TABLE                                                           ______________________________________                                                                              Leaked                                                                        Num-                                           Container                                                                             Metallic               bers/-                                         Body    Cover     OL/L    W    1000                                    ______________________________________                                        Comparison                                                                             Aluminum  Aluminum  0.8   1.0 y                                                                              0                                     Example 1                                                                     Comparison                                                                             Aluminum  Aluminum  0.3   1.0 y                                                                              2                                     Example 2                                                                     Concrete Plastic   Aluminum  0.3   0.8 y                                                                              0                                     Example 1                                                                     Concrete Plastic   Aluminum  0.05  0.8 y                                                                              0                                     Example 2                                                                     Reference                                                                              Plastic   Aluminum  0.02  0.8 y                                                                              1                                     Example 1                                                                     Reference                                                                              Plastic   Aluminum  0.3   0.5 y                                                                              0                                     Example 2                                                                     Reference                                                                              Plastic   Aluminum  0.3   0.4 y                                                                              25                                    Example 3                                                                     Reference                                                                              Plastic   Aluminum  0.3   0.1 y                                                                              30                                    Example 4                                                                     ______________________________________                                         where y = 3M + 2P                                                        

It was found from the Table that fewer containers were free from leakagein cases where the width W of the seamed portion 103 ranged from 0.5y to1.0y.

(4-1-4 Effects)

According to this invention, a container provided with a metallic coverhaving an improved sealing function and having a flanged portion that ishardly damaged can be obtained by forming the seamed portion so as tohave a specific shape by the suitable double seaming operation of thisinvention.

4.2 Container provided with a metallic cover having a seamed portionhaving specific seamed width and seamed height

(4-2-1 Basic Structure)

FIGS. 37 to 40 show a container provided with a metallic cover having aseamed portion having specific seamed width and seamed height.

A container provided with a metallic cover will be first described. Asshown in FIGS. 37 and 38, the container 10 provided with the metalliccover is composed of a plastic container body 14 filled with a content19 and a metallic cover 11.

The container body 14 provided with a flanged portion 15 is formed byheat forming, in a known heating, method, a laminated material of thestructure of polypropylene/bonded layer/ethylene vinyl alcoholcopolymer/bonded layer/polypropylene, then heat pressing the flangedportion 15 to reduce the thickness thereof and finally cutting the widththereof. The heat formation of the laminated material may be performedby a pressure formation, a vacuum formation or the combination thereof,or a plug-assist formation.

The metallic cover 11 provided with a peripheral edge portion 12 isformed of an aluminum or tinplate.

A container seaming device 110 comprises a vertically movable supportingcylinder 111, a rotary lifter 112 which is supported by the cylinder 111through a bearing member 111a and on which a container 10 provided witha metallic cover is mounted, and a rotary chuck 113 disposed above therotary lifter 112 and adapted to hold under pressure the container 10between the lifter 112 and the chuck 113. First and second seaming rolls114 and 115 for carrying out the seaming operation to the container 10are disposed external to the rotary chuck 113. The first and secondseaming rolls 114 and 115 are constructed to be movable in a radialdirection of the container 10 provided with the metallic cover and theserollers 114 and 115 press the peripheral portion 12 of the metalliccover 11 from the outer side thereof while freely rotating to therebyroll seam the peripheral portion 12 of the metallic cover 11 to theflanged portion 15 of the container body 14.

As shown in FIGS. 39 and 40, the first and second seaming rolls 114 and115 are provided with outer peripheries in which annular grooves 114aand 115a are formed for pressing the peripheral portion 12 of themetallic cover 11 seaming the portion 12 to the flanged portion 15 ofthe container body 14 in engagement with the peripheral portion 12. One,for example 114a, of these annular grooves 114a and 115a is limited inthe vertical width h₁ by an upper projection 125 and a lower projection126 of the seaming roll 114. Similarly, the vertical width h₂ of theannular groove 115 is also defined by an upper projection 127 and alower projection 128 of the second seaming roll 115. These grooves 114and 115a are of substantially U-shaped cross sections.

(4-2-2 Manufacturing Method)

A container 10 provided with a metallic cover in which a peripheralportion 12 of a metallic cover 11 is loosely seamed to a flanged portion15 of a plastic container body 14 filled with a content 19 is mounted onthe rotary lifter 112 (FIG. 37).

The supporting cylinder 111 is upwardly moved to upwardly move therotary lifter 112 together with the container 10 provided with themetallic cover to thereby hold the container 10 between the rotarylifter 112 and the rotary chuck 113 under the pressed condition (dottedline in FIG. 37). The rotary lifter 112 and the rotary chuck 113 arethen rotated with the container 10 held therebetween, thus the container10 itself also being rotated.

The first seaming roll 114 is moved radially inwardly to press theperipheral portion 12 of the metallic cover 11 and freely rotated tocarry out the first seaming operation (single seaming) between theflanged portion 15 of the container body 14 and the peripheral portion12 of the metallic cover 11.

Subsequently, the first seaming roll 114 is moved radially outwardly ina direction apart from the peripheral portion 12 of the metallic cover11. The second seaming roll 115 is then moved radially inwardly to pressthe peripheral portion 12 and freely rotated to carry out the secondseaming operation (double seaming) between the peripheral portion 12 ofthe metallic cover 11 and the flanged portion 15 of the container body14.

The seaming operation of the container 10 provided with the metalliccover is thus completed by these double seaming operations.

As shown in FIG. 38, the seamed portion 123 of the container 10 providedwith the metallic cover after the seaming operation between theperipheral portion 12 of the metallic cover 12 and the flanged portion15 of the container body 14 has a seamed width W and a seamed height T.The overlapped length of the seamed portion 123 is designated by OL.

(4-2-3 Concrete Example)

Concrete examples according to this invention will be describedhereunder.

EXAMPLE 4-1

A plastic container body 14 provided with a flanged portion 15 having athickness of 0.45 mm and a width of 2.20 mm and a metallic cover 11having a thickness of 0.3 mm were first prepared and a peripheral edgeportion 12 of the metallic cover 11 was seamed to the flanged portion 15of the plastic container body 14 under seaming conditions of:

Groove width of the first seaming roll h₁ =2.4 mm

Groove width of the second seaming roll h₂ =2.6 mm

Roll seaming load: 50 kgf

Under these conditions, the width of the seamed portion 123 was changedvariously.

Tests in connection with the seamed outer appearances and the sealingperformance were carried out to the containers 10 provided with themetallic covers which have been subjected to the seaming operation underthe conditions described above and the results of the tests are shown inthe following Table 4-1.

Regarding the appearance tests, the presence or absence of a vee, afalse seam, a cutover, and a sharp seam were performed through thevisual inspections of the seamed portions 123. Regarding the sealingperformance tests, container bodies 14 each filled with a liquid-statesuspected material were sterilized under the condition of heatingtemperature of 120° C. and a pressure of 1.5 kg/cm² for 30 min.Thereafter, the container bodies 14 were reserved for two weeks in theconstant temperature room of 37° C. The swelling and leakage of thecontents were thereafter inspected. 100 numbers of container bodies weretested for the respective tests.

                  TABLE 4-1                                                       ______________________________________                                        Seamed Width             Sealing                                              (W)           Appearance Performance                                          ______________________________________                                        1.50 (m/m)    x          Δ                                              1.60          ∘                                                                            ∘                                        1.70          ∘                                                                            ∘                                        1.80          ∘                                                                            ∘                                        1.90          ∘                                                                            ∘                                        2.00          ∘                                                                            ∘                                        2.10          x          x                                                    ______________________________________                                    

It was found, that when the seamed width is over 2.00 m/m, theoverlapped portion between the peripheral portion 12 of the metalliccover 11 and the flanged portion 15 of the container body 14 was notwell seamed and the upper portion of the seamed portion 123 wasextremely swelled and that when the seamed width is below 1.60 m/m, thecompression was too strong to parallelly overlap the flanged portion 15and the peripheral portion and, in an adverse case, a crack was formedin the flanged portion 15. According to these tests, it was found to bepreferred that the seamed width be in a range of 1.60 to 2.00 m/m.

EXAMPLE 4-2

Tests in connection with the seamed outer appearances and the sealingperformance were carried out to the containers 10 provided with themetallic covers which have been subjected to the seaming operation underthe conditions substantially the same as those of the Example 4-1 byvariously changing the width of the groove of the first seaming roll andthe results of the tests are shown in the following Table 4-2.

                  TABLE 4-2                                                       ______________________________________                                        Groove Width             Sealing                                              (h.sub.1)     Appearance Performance                                          ______________________________________                                        2.00 (m/m)    x          x                                                    2.20          ∘                                                                            ∘                                        2.40          ∘                                                                            ∘                                        2.60          ∘                                                                            ∘                                        2.80          x          x                                                    ______________________________________                                    

The tests showed that the groove width h₁ of the first seaming roll of2.20 to 2.60 mm is desired.

EXAMPLE 4-3

Tests in connection with the seamed outer appearances and the sealingperformance were carried out to the containers 10 provided with themetallic covers which have been subjected to the seaming operation underthe conditions substantially the same as those of the Example 4-1 byvariously changing the width of the groove of the second seaming rolland the results of the tests are shown in the following Table 4-3.

                  TABLE 4-3                                                       ______________________________________                                        Groove Width             Sealing                                              (h.sub.2)     Appearance Performance                                          ______________________________________                                        2.00 (m/m)    x          x                                                    2.40          ∘                                                                            ∘                                        2.60          ∘                                                                            ∘                                        2.80          ∘                                                                            ∘                                        3.00          Δ    x                                                    ______________________________________                                    

According to the tests, it was found that in case of the groove width h₂of the second seaming roll being over 80 m/m, the sealing performancewas made worse because of turnaround of bodyhook revolving the firstseaming work or excessively lower clearance. It was therefore found thatthe groove width h₂ of the second seaming roll is desired in the rangeof 2.40 to 2.80 mm.

EXAMPLE 4-4

The comparison tests were carried out under substantially the sameseaming conditions as those of the Example 4-1 and the comparison ofthis invention with the conventional technology was carried out withrespect to the shapes of the second seaming roll 115.

Namely, the seaming working was performed by using the second seamingroll 115 of this invention which is provided with an annular groove 115ahaving a U-shaped section (FIG. 40) and the second seaming roll 115 ofconventional type provided with no lower projection and with an annulargroove 115a of not U-shaped section (FIG. 41).

According to this comparison test, it was found that the overlappedlength OL of the seamed portion 123 was over 0.70 m/m according to thisinvention and the content in the container was free from the leakage inthe reservation test. On the other hand, according to the conventionalexample, the overlapped length On of the seamed portion 123 was merelyabout 0.20 m/m and the leakage of the content of sixty-two containerswas observed with respect to one hundred of containers in thereservation test.

It was found from this result that the seaming operation could becarried out in good conditions when the annular groove 115a of thesecond seaming roll has a U-shaped section.

In the above tests, the plastic container 14 provided with the flangedportion 15 having the thickness of 0.45 mm and the width of 2.2 mm wasutilized, but it has been found that substantially the same results wereattained by utilizing the container body provided with the flangedportion having the thickness of 0.25 to 0.55 mm and the width of 1.6 mmto 2.6 mm.

(4-2-4 Effects)

According to this invention, the seamed portion 123 superior in thesealing performance is formed between the flanged portion 15 of thecontainer body 14 and the peripheral edge portion 12 of the metalliccover 11, whereby the container 10 provided with the metallic cover freefrom the leakage of the contents can be easily and simply formed.

§5. Fifth Embodiment of Container provided with Metallic Cover(Container in which deoxidizer adheres)

5.1 Container provided with a metallic cover in which a deoxidizeradheres

(5-1-1 Basic Structure)

FIGS. 42 and 43 Show a container provided with a metallic cover in whicha deoxidizer is sticked.

The container 10 provided with the metallic cover is formed by seamingthe peripheral edge portion 12 of the metallic cover 11 to the flangedportion 15 of the plastic container body 14.

A deoxidizer 130 is firmly sticked to the inner surface of the metalliccover 11 and iron group deoxidizer may be adopted for the deoxidizer130.

The plastic container body 14 used for his embodiment is notspecifically limited in the material to be utilized and any material maybe utilized as far as the material is endowed with the hardness and thestrength sufficient for withstanding the seaming force. For example, thecontainer body 14 can be formed by thermally forming a laminatedmaterial of the structure of polypropylene/ethylene vinyl alcoholcopolymer/polypropylene or the container body 14 can be formed byinserting the sheet blank forming the shell portion and the bottomportion of the container body 14 into a mold and injecting an injectionmolding resin along the sheet blank.

A laminated layer structure, not shown, of an epoxy resin layer and adenatured polyolefine layer is preliminarily coated on substantially theentire inner surface of the metallic cover 11.

(5-1-2 Manufacturing Method)

The seaming working of the container 10 provided with the metallic coverwill be described hereunder.

A content 19 first fills in the plastic container body 14.

The metallic cover 11 is thereafter applied to the container body 14with the peripheral portion 12 overlapped to the flanged portion 15. Thecontainer body 14 and the metallic cover 11 are then elevated by alifter 142 as shown in FIG. 43 and pressed vertically between the lifter142 and a chuck 143 arranged at the upper portion of the lifter 142.

The peripheral edge portion 12 of the metallic cover 11 is roll seamedto the flanged portion 15 of the container body 14 by a plurality ofseaming rolls 140 under the pressed condition between the lifter 142 andthe chuck 143. The roll seamed peripheral portion 12 of the metalliccover 11 is thereafter heated to fuse the denatured polylefine layercoated on the inner surface of the metallic cover 11, whereby theperipheral portion 12 of the metallic cover 11 and the flanged portion15 of the container body 14 can be completely fused and bonded tothereby obtain the container 10 provided with the metallic cover.

According to this embodiment, since the deoxidizer 130 is adhered on theinner surface of the metallic cover 11, the oxygen in the containerprovided with the metallic cover is captured by the deoxidizer 130 and,hence, the oxygen concentration in the container 10 is reduced, wherebythe oxidation of the content 19 can be prevented and the reservingperformance for the content can be improved.

For example, when Agiless (Commercial Name of MITSUBISHI GAS CHEMICALCO.) is utilized as the deoxidizer 130, the oxygen concentration in thecontainer 10 provided with the metallic cover is reduced to about lessthan 0.1%.

In the described embodiment, the deoxidizer 130 is secured to the innersurface of the metallic cover 11, but, in an alternation, the deoxidizer130 may be secured to the inner surface of the container body 14, forexample, on the bottom surface or the side surface. In such alternation,it is preferred to pack the contents 19 in the form of a powder.

(5-1-3 Effects)

According to this invention, the oxygen concentration in the container10 provided with the metallic cover is reduced by the deoxidizer 130secured on the inner surface of the metallic cover 11 or the containerbody 14, whereby the oxidation of the contents 19 in the container 10can be prevented and the preserving performance for the content can beimproved.

§6. First Embodiment of Manufacturing Method of Container Body ofContainer provided with Metallic Cover (Manufacturing method in which aguide is mounted in the container body during a pressing process or acutting process)

6.1 Manufacturing method of a container body in which a guide member ismounted

(6-1-1 Basic Structure)

FIGS. 44 to 48 are views representing a manufacturing method in a casewhere a guide member is mounted in a container body.

With reference to FIG. 46, processes for manufacturing a mold product ofthe container body 214 by a thermoforming treatment due to a generalsheet forming process will be described hereunder.

A plastic sheet 230 is first heated by a heating device 231 and aproduct 220 is molded by a usually known molding method by means of amold 232. A pressure forming or vacuum forming, or a combination thereofmay be utilized for this molding method.

With respect to the cross section of one container body 214 constitutingthe product 220, as shown in FIG. 47, the shell portion 214a and thebottom portion 214b each has a thickness and strength sufficient forwithstanding the pressure applied thereto at the double seaming process.However, a flanged portion 215 thus formed has a large thickness t whichis not applicable for the double seaming process.

It is desired, for the plastic sheet 230 for forming the container body214 to be formed of a plastic laminated material having a lesspermeability with respect to an oxygen gas and water vapor in order topreserve food in the container, that the oxygen gas barrier property isless than 0.8 cc/100 cc; 24 hrs. atm., (20° C., 90% RH) and the H₂ O gasbarrier property is less than 0.2 g/100 cc; 24 hrs. atm. (40° C., 90%RH).

In the subsequent steps, a plurality of container bodies 214constituting the mold product 220 are separated one by one. Thethickness of the flanged portion 215 is thereafter reduced (pressingprocess) and the width of the flanged portion 215 is cut so as to have apredetermined width (cutting process).

The pressing and cutting processes of the flanged portion 215 will bedescribed hereunder with reference to FIGS. 44, 45 and 48, in which FIG.48 is an enlarged view of a portion E shown in FIG. 44.

Referring to FIGS. 44 and 48, a pressing device for carrying out thepressing process comprises a press male mold half 221 and a press femalemold half 222 arranged above the press male mold half 221 to bevertically movable.

The press female mold half 222 has a shape, as shown in FIG. 48, havinga thickness increasing from the inner side towards the outer sidethereof. For this reason, the excessive part of the flanged portion 215is shifted outward during the pressing process, so that the excessiveportion never form an inside massive portion, whereby the pressingprocess can be performed with high accuracy.

A guide member 223 having an outer shape corresponding to the innershape of the container body 214 separated from the mold product 220 isinserted into the container body 214 and then mounted on the press malemold half 221 with the flanged portion 215 downward.

In such a case, the container body 214 is secured under a vacuum to theguide member by means of an air communication passage 223a formed in theguide member 223.

In the next step, the press female mold half 222 is lowered to press theflanged portion 215 between the press male mold half 215 and the pressfemale mold half 222 so as to have a predetermined thickness. The pressfemale mold half 222 may be driven by a hydraulic means or a pneumaticmeans.

When the thickness of the flanged portion 215 reaches to thepredetermined value, the press female mold half 222 is lifted and thecrushing operation of the flanged portion has been completed. It isdesired for the flanged portion to have a thickness t in the range of0.25 to 0.9 mm.

It is also desired that the thickness t of the flanged portion 215 iswithin the range of 0.9 t₀ ≧t₁ ≧0.4 t₀ and, preferably, 0.9 t₀ ≧t₁ ≧0.6t₀, where t₀ is an original thickness of the flanged portion 215 and t₁is a thickness after the pressing. Namely, in the range of t₁ ≧0.9 t₀,the thickness of the flanged portion is too large to sufficientlycompensate for the unevenness of the thickness and to carry out adesired double seaming process.

In the range of t₁ ≦0.4 t₀, the flanged portion 215 is excessivelycrushed, so that a relatively large volume of plastic material forforming the flanged portion 215 will be extruded. For this reason, aseries of lumps may be formed around the pressed portion, or the flangedportion 215 may be thermally deformed and, hence, the flanged portion215 having a uniform thickness will not be formed.

Since the guide member 223 is inserted into the container body 214during the pressing process, the stable positioning of the containerbody 14 will be achieved and the pressing process can thus be performedwith high accuracy. The formation of a series of lumps in the containerbody 214 can be prevented, so that the shape of the flanged portionnever be damaged.

The container body 214 is thereafter cooled for the predetermined timeand, thereafter, the flanged portion 215 is cut by means of the cuttingdevice as shown in FIG. 45 so as to have a predetermined width.

The cutting device 229 comprises a cut male half 226 and a cylindricalcut female half 228 disposed above the cut male half 226 to bevertically movable.

A guide member 227 having an outer shape corresponding to an inner shapeof the container body 214 is inserted into the container body 214 andthe container body 214 is arranged on the cut male half 226 with theflanged portion downward. During this process, the container body 214 isvacuum secured to the guide member 227 by means of a vacuuming passage227a formed in the guide member 227.

The cut female half 228 is thereafter lowered to punch out the flangedportion 215 in engagement with the peripheral portion of the cut malehalf 226 to form the flanged portion 215 having a predetermined width.It is desired for the flanged portion 215 to have a width having athickness of about 1.0 to 2.5 mm. Since the guide member 227 is insertedduring the cutting process, the container body 214 is stably positionedon the cut male half 226 and the flanged portion 215 is therefore cutwith high accuracy.

With the embodiment described above, it may be possible to arrange acooling pipe inside the guide member 223 of the pressing device and theguide member 227 of the cutting device to cool the guide members. Insuch case, the transferring of the heat to the container body 214 duringthe pressing and cutting processes can be effectively prevented, wherebythe deformation of the container body 214 can also be surely prevented.

(6-1-2 Effects)

According to this invention, since the container body 214 can be stablyheld during the working processes of the container body 214 by the guidemembers 223 and 227, the working precision can be improved and, hence,the container provided with the metallic cover can be formed with highperformance.

§7. First Embodiment of Manufacturing Method of Container provided withMetallic Cover (Manufacturing method by utilizing a retainer)

7.1 Manufacturing method of a container provided with a metallic coverby utilizing a retainer

(7-1-1 Basic Structure)

FIGS. 49 to 51 show a device for manufacturing a container provided witha metallic cover by utilizing a retainer.

A container seaming device 250 is provided with a turret 252 whichcarries out a sliding rotation in an arrowed direction L₁ shown in FIG.49 on a stationary plate 251 and the turret 252 is provided with aplurality of holes 255, six for example, communicating with a supplyline 257 and a discharge line 258. The holes 255 serve to receive andconvey the container 210 provided with the metallic cover comprising asingle or multiple layered container body 214 and the metallic cover211.

A pair of first rolls 253 and a pair of second rolls 254 are disposed soas to surround the container 210 provided with the metallic cover at aportion above the turret 252, the rolls 253 and 254 constituting theseaming device 256. The first and second paired rolls 253 and 254revolve around the central portion 256a of the seaming device 256 in anarrowed direction shown in FIG. 49 and rotate themselves.

The paired rolls 253 and 254 are also movable in directions towards thecentral portion 256a of the seaming device 256, i.e. in the radialdirection thereof.

The stationary plate 251 is provided with an opening 270 positioneddirectly below the seaming device 256. The holes 255 of the turret 252pass directly below the seaming device 256 and, accordingly, the holes255 and the opening 270 have substantially the same shape. A lifter 265is arranged in the opening 270 vertically movably.

(7-1-2 Function)

The function of this embodiment will be described hereunder.

The container body 214 is first mounted in a recess 267a formed in theretainer 267, which has an outer configuration of substantiallyrectangular parallel-piped as a whole. The retainer 267 is conveyedtogether with the container 210 provided with the metallic cover whileprotecting the container body 214 of the container 210 during a timewhen the container 210 is conveyed to the seaming device 256, seamedthere by the seaming device 256 and discharged therefrom.

The recess 267a of the retainer 267 has an inner shape corresponding tothe outer shape of the bottom surface of the container body 214.

In the next step, the container body 214 is filled with a content, notshown, under the heated condition (about more than 60° C.) and themetallic cover 211 is thereafter loosely fitted to the container body214.

The container 210 composed of the container body 214 and the metalliccover 211 is supplied to the hole 255 of the turret 252 together withthe retainer 267 from the supply line 257.

The container 210 provided with the metallic cover and the retainer 267are conveyed to a position directly below the seaming device 256 by therotation of the turret 252. During this conveyance, the hole 255 of theturret 252 reaches a position corresponding to the opening 270 of thestationary plate 251 and the retainer 267 mounted with the container 210provided with the metallic cover is supported by he lifter 256 arrangedin the opening 270.

In the next step, as shown in FIG. 50, the rotation of the turret 252stops and the lifter 265 rises to upwardly move the container 210provided with the metallic cover and the retainer 267, whereby thecontainer 210 and the retainer 267 are held under the pressed conditionbetween the lifter 265 and the chuck 266 and under these conditions, theseaming operation is carried out by means of the seaming device 256 tothe container 210 provided with the metallic cover.

A pair of first rolls 253 is radially inwardly moved and then moved soas to abut against the container 210 provided with the metallic cover,whereby the first single seaming process is carried out for seaming theperipheral portion 212 of the metallic cover 211 to the flanged portion215 of the container body 214. The first rolls 253 are then movedradially outwardly and a pair of second rolls 254 are then movedradially inwardly, whereby the second double seaming process is carriedout for seaming the peripheral portion 212 to the flanged portion 215.The double seaming operation can thus be performed by carrying out thesefirst and second seaming processes to the container 210 provided withthe metallic cover as shown in FIG. 51.

During these seaming processes, since the container 210 is supportedunder the pressed condition between the lifter 265 and the chuck 266,the container 210 never rotates and the seaming process can thus bestably performed.

The lifter 265 is thereafter lowered into the opening 270 and the turret252 again begins to rotate.

As described above, according to this embodiment, the container body 214is mounted in the recess 267a of the retainer 267, the container body214 softened by packing the heated contents therein never swellsoutwardly even when the container body 214 is pressed in the verticaldirection. Furthermore, the container body 214 is conveyed in the statemounted in the recess 267a of the retainer 267 of the rectangularpallalerodize structure, so that the conveyance can be stably achievedand, accordingly, the container 210 provided with the metallic cover canbe free from the leakage of the contents.

(7-1-3 Effects)

According to this invention, since the container provided with themetallic cover can be stably conveyed, the container 210 is free fromthe leakage of the contents. Moreover, the container body 214 neverdeforms during the seaming process, so that the yield of the productscan be improved.

§8. Second Embodiment of Manufacturing Method of Container provided withMetallic Cover (Manufacturing method in which a container provided witha metallic cover is sterilized under the condition that a pressuredifference between inner and outer pressures is made constant)

(8-1-1 Basic Structure)

FIGS. 52 and 53 show one embodiment in which the container provided withthe metallic cover is manufactured by heat sterilizing the same underthe constant pressure difference.

Referring to FIG. 52, a content 219 is packed in the plastic containerbody 214 with a space remaining at the upper portion of the containerbody 214.

An aluminum or tinplate metallic cover 211 is then fitted to thecontainer body 214 with the peripheral portion 212 of the metallic cover211 being overlapped with the flanged portion 215 of the container body214. The peripheral portion 212 is then seamed to the flanged portion215 by means of a suitable seaming device.

In this Seaming operation, a laminated material composed of an epoxyphenol and a denatured polyolefine is preliminarily coated on the rearsurface of the metallic cover 211.

The plastic container body 214 utilized in this embodiment is notlimited in the material and a laminated material mainly composed of anolefine resin, polypropylene may be utilized as far as the material hashardness and strength sufficient for withstanding the seaming operation.

The peripheral portion 212 of the metallic cover 211 and the flangedportion 215 of the container body 214 after the seaming operation areheated to fuse the denatured polyolefine preliminarily coated on theinner surface of the metallic cover 211 to thereby bond the flangedportion 215 and the peripheral portion 212.

In the next step, as shown in FIG. 52, the seamed container body 214 andthe metallic cover 211 are set a constant differential pressure typesterilizing oven 280 and heat sterilized at a temperature of about 120°C. for about 30 min. whereby the container 210 provided with themetallic cover can be obtained. The sterilizing oven 280 serves to heatthe container 210 provided with the metallic cover and to apply apressure from the outside thereof to keep constant the pressuredifference between the inner and outer pressures of the container 210during the heat sterilizing process.

According to this embodiment, since the inner and outer pressures of thecontainer 210 provided with the metallic cover can be maintainedconstant during the heat sterilizing process, the container body 214 isnever deformed by the expansion of air even if the air remains of about20 volume %, for example, in the inner upper portion of the containerbody 214.

(8-1-2 Effects)

According to this invention, the container body 214 is never deformed bythe air remaining in the container body 214 during the heat sterilizingprocess, so that the product of the container 210 provided with themetallic cover can be obtained with high accuracy and quality and theyielding of the products can be also improved.

§9. First Embodiment of Manufacturing Apparatus for Container providedwith Metallic Cover (Press-cut device of a container body)

9.1 Press-cut device having an intermediate bed

(9-1-1 Basic Structure)

FIGS. 54 to 56 represent a press-cut device provided with anintermediate bed. Referring to FIG. 54, a press-cut device 310 includesan intermediate bed 313 disposed on a base through a crank mechanism 312to be vertically movable so as to take upper, intermediate and lowerpositions in the vertical direction. An upper stationary table 315 isarranged at a portion above the intermediate bed 313.

As shown in FIG. 54, a press male half 321a is disposed at a righthandportion, as viewed, above the intermediate bed 313 and a press femalehalf 321b corresponding to the press male half 321a is disposed belowthe upper stationary table 315, the press male and female halves 321aand 321b constituting a pressing device 321. In the meantime, a cut malehalf 323a is disposed at a lefthand portion, as viewed, above theintermediate bed 313 and a cut female half 323b corresponding to the cutmale half 323a is disposed below the upper stationary table 315, the cutmale and female halves constituting a cutting device 323. A coolingtable 322 is disposed at a central portion above the intermediate bed313.

Guide members 325, 326 and 327, which are mounted in a plastic containerbody 345 (FIG. 56) are arranged above the press male half 321a, thecooling table 322 and the cut male half 323a. These guide members 325,326 and 327 have outer shapes corresponding to the shell portion 347 andthe bottom portion 348 of the container body 345 and serve to secure thecontainer body 345 to the predetermined position.

As further shown in FIG. 54, a supply pipe 328 for supplying thecontainer body 345 is disposed on the righthand side of the upperstationary table 315 and a supply table 330 corresponding to the supplypipe 328 is disposed on the intermediate bed 313. The supply pipe 328serves to supply the container body 345, which is formed from a plasticsheet by a generally known thermoforming method and is provided with aflanged portion 346, to the supply table 330. A discharge pipe 329,communicating with the cut female half 323b, for discharging thecontainer body 345 is disposed on the lefthand side of the upperstationary table 315.

A conveyer device 317 is arranged between the intermediate bed 313 andthe upper stationary table 315 for horizontally conveying the containerbody 345 subsequently from the supply table 330 to the press male half321a of the pressing device 321, the cooling table 322 and the cut malehalf 323a of the cutting device 323.

The base 311, the crank mechanism 312 and the intermediate bed 313 areentirely covered by a cover 316.

The pressing device 321 will be described in detail hereunder withreference to FIG. 55.

The press male half 321a of the pressing device 321 is disposed on theintermediate bed 313 through the pressing table 336 and the guide member325 is disposed on the press male half 321a. The press male half 321aand the press female half 321b act in combination to press the flangedportion 346 of the container body 345 so as to have a predeterminedthickness and heaters 333 and 335 are therefore disposed inside thepress male and female halves, respectively. A cooling water passage 334is formed in the guide member 325 for cooling the shell portion 347 andthe bottom portion 348 of the container body 345.

The cutting device 323 will be described hereunder with reference toFIG. 56.

The cut male half 323a of the cutting device 323 is disposed on theintermediate bed 313 through the cutting table 341 and the guide member327 is disposed on the cut male half 323a. The cut male half 323a andthe cut female half 323b act in combination to cut the outer peripheryof the flanged portion 346 of the container body 345 so as to have apredetermined width. An ejector 340 for ejecting and removing cutpieces, not shown, of the flanged portion 346 from the cut female half323b is arranged at a circumferential portion of the cutting holding thecontainer body 345 is located in an upwardly directed manner at thelower end portion of the inner surface of the cut female half 323b.

(9-1-2 Effects)

The function of this embodiment of the construction described above willbe described hereunder.

A plastic sheet having a thickness necessary for the formation of acontainer is preliminarily heated by a usual thermoforming method andthe container body 345 provided with the flanged portion 346 is formedby means of a mold.

In the next step, the container body 345 is supplied on the supply table330 by means of the supply pipe 328 and the intermediate bed 313 isarranged at an intermediate portion. The container body 345 is held by agripper, not shown, of the conveyer device 317. The intermediate bed 313is thereafter lowered to the lower position and the container body 345is conveyed on the press male half 321a.

The intermediate bed 313 is then elevated through the intermediateposition to the upper position, at which the guide member 325 is mountedin the container body 345 to secure the same. In this process, thecontainer body 345 may be securely attached to the guide member 325 byforming a vacuuming hole, not shown, in the guide member 325. The pressmale half 321b is slightly lowered by the operation of a hydraulic meansto press the flanged portion 346 of the container body 345 between thepress male half 321a and the press female half 321b so as to have apredetermined thickness.

During these processes, since the flanged portion 346 is heated by theheaters 333 and 335 disposed in the press male half 321a and the pressfemale half 321b, the pressing working can be carried out with highaccuracy and, moreover, the shell portion 347 and the bottom portion 348of the container body 345 are cooled by the cooling water passing thecooling passage 334, so that the container body 345 is free from thethermal deformation.

In the next step, the intermediate bed 313 is lowered to theintermediate position and the container body 345 is held by the gripperof the conveyer device 317. The intermediate bed 313 is then furtherlowered to the lower position and the container body 345 is conveyed onthe cooling table 322 by the conveyer device 317. The intermediate bed313 is again lifted upwardly to the upper position through theintermediate position and, thereafter, lowered to the intermediateposition. During this elevation of the intermediate bed, the containerbody 345 is mounted in the guide member 326 disposed on the coolingtable 322 and cooled. It is desirable to form a cooling water flowpassage in the guide member 326 for,cooling the container body 345.

The container body 345 is conveyed on the cut male half 323a by theconveyer device 317 after the intermediate bed 313 has been lowered tothe intermediate position with the container body 345 being held by thegripper of the conveyer device 317.

Subsequently, the intermediate bed 313 is lifted upwardly to the upperposition and, during this time, the container body 345 is secured to theguide member 327 and, simultaneously, the peripheral portion of theflanged portion 346 of the container body 345 is cut between the cutmale half 323a and the cut female half 323b to thereby arrange the widthof the flanged portion to a predetermined value. In tis process,accurate cutting may be performed by providing a vacuum hole in theguide member 327 to firmly suck the container body 345 to thepredetermined position.

The container body having the flanged portion 346 the thickness and thewidth of which are thus be adjusted is moved inside the cut female half323b and held by the holding member 344. The container body 345 in theholding member 344 is conveyed upwardly by the next container body 345which will be moved inside the cut female half 323b and the containerbody 345 is then discharged through the discharge pipe 329. In thecutting process, the cut pieces will be removed from the cut male half323a by the ejector 340 outwardly of the conveyer device 317.

As described above, according to this embodiment, the container body.345 is continuously moved to the pressing device 323, the cooling table322 and the cutting device 323 by the conveyer device 317, whereby theflanged portion 346 of the container body 345 can be pressed and cut bythe single device easily and precisely.

In the described embodiment, the press male half 321a is mounted to theintermediate bed 313 and the press female half 321b is mounted to thestationary table 315, but the press male half 321a may be mounted to thestationary table 315 and the press female half 321b may be mounted tothe intermediate bed 313. Likely, the cut female half 323b may bemounted to the intermediate bed 313 and the cut male half 323a may bemounted to the stationary table 315.

(9-1-3 Effects)

According to this invention, the container body 345 is continuouslyconveyed from the pressing device 321 to the cutting device 322 and,during this conveyance, the intermediate bed 313 is moved vertically,whereby the flanged portion 346 of the container body 345 can be easilyand precisely pressed and cut so as to have a predetermined thicknessand width and, therefore, the flanged portion can be securely seamed bythe peripheral portion of the metallic cover, resulting in theproduction of the container provided with the metallic cover with highquality.

9.2 Heat-press device provided with a liner for limiting a gap between apress male half and a press female half

(9-2-1 Basic Structure)

FIGS. 57 and 58 are views showing a heat-press device provided with aliner, in which FIG. 58 is an enlarged view of the portion F shown inFIG. 57.

A container body to be pressed is first described hereunder. As shown inFIG. 57, a container body 345 is formed by heating a plastic sheethaving a thickness necessary for the formation of the container body dueto a general thermoforming method and forming the sheet by means of amold. The container body thus formed is composed of a shell portion 347,a bottom portion 348 and a flanged portion 346 formed at the opening endof the shell portion 347. The container body 345 is utilized formanufacturing a container provided with a metallic cover. Namely, thecontainer body is filled with contents and a peripheral portion of ametallic cover is seamed to the flanged portion 346 to thereby form thecontainer provided with the metallic cover.

The heat pressing device will be next described hereunder. Referring toFIG. 57, the heat pressing device 321 is composed of a press male half321a and a press female half 321b disposed above the press male half321a to be separable therefrom. A guide member 325 having an inner shapecorresponding to the shell portion 347 and the bottom portion 348 of thecontainer body 345 is disposed above the press male half 321a. The guidemember 325 serves to incorporate the container body 345 therein to apredetermined position and facilitate the pressing operation withoutdeforming the container body 345.

The press male and female halves 321a and 321b serve to press theflanged portion 346 of the container body 345 so as to have apredetermined thickness and heaters 333 and 335 are arranged to theouter peripheral portions of the press male and female halves 321a and321b, respectively.

A liner 350 is arranged in an annular fashion to the upper peripheraledge of the press male half 321a to secure the thickness of the flangedportion 346. The liner 350 is arranged outside the area corresponding tothe flanged portion 346 of the container body 345 and abuts against thepress female half 321b located above the area to determine the thicknessof the flanged portion to a predetermined value. A vacuuming hole 351communicating with the vacuuming side is formed in a penetrating mannerin the press male half 321a and the guide member 325 and the vacuuminghole 351 is opened to the upper end of the guide member 325.

(9-2-2 Function)

The function of this embodiment of the structure described above will bedescribed hereunder.

A plastic sheet having the thickness necessary for the formation of acontainer body due to a general thermoforming method is first heated andthe heated sheet is preliminarily formed into a container body 345provided with a flanged portion 346 by means of mold.

In the next step, the press female half 321b is separated from the pressmale half 321a and the container body 345 is mounted in the guide member325 disposed on the press male half 321a in an inverted manner. Thecontainer body 345 is vacuum sucked through the vacuuming hole 351 tosecure the container body 345 to the predetermined position. The pressfemale half 321b approaches the press male half 321a to press thecontainer body 345 so that the flanged portion 346 of the container body345 is pressed to have a predetermined thickness.

During the pressing operation, the flanged portion 346 is heated by theheaters 333 and 335 arranged to the outer peripheral portions of thepress male half 321a and the press female half 321b, so that thepressing operation can be securely performed. A predetermined gap, asshown by an arrow L in FIG. 58, for example, is limited between thepress male half 321a and the press female half 321b by the abutment ofthe liner 350 attached to the upper edge of the press male half 321aagainst the press female half 321b, so that the thickness of the flangedportion 346 can be precisely determined to a predetermined value.Moreover, since the container body 345 is secured to the predeterminedposition by the sucking function of the vacuuming hole 351 formed in theguide member 325, the pressing working can be effectively performedwithout thermally deforming the container body 345.

The press female half 321b is then separated from the press male half321a and the container body 345 is removed from the guide member 325. Inthis process, the container body 345 may be easily removed from thepress male and female halves 321a and 321b by blowing air through airsupply pipes, not shown, provided for the press male and female halves321a and 321b.

The container body 345 is thereafter conveyed to a cutting device, notshown, by which the outer portion 346a (FIG. 58) of the flanged portion346 not pressed is cut by the cutting device to thereby make the widthof the flanged portion 346 to the predetermined value.

In the next step, the container body 345 is filled with a content andthe peripheral portion of the metallic cover is seamed to the flangedportion 346 of the container body 345 to thereby form a containerprovided with a metallic cover.

As described hereinbefore, according to this embodiment, the spacebetween the press male half 321a and the press female half 321b is setto a predetermined value by the liner 350 located to the upperperipheral edge of the press male half 321a, whereby the flanged portion346 of the container body 345 can be pressed so as to have apredetermined thickness with high accuracy and the pressing working canbe effectively performed without deforming the container body bymounting the same in the guide member 325.

(9-2-3 Specific Example)

The relationship between the thickness of the flanged portion and theliner 350 in a case where the thickness of the liner 350 was variouslychanged is shown in the following table.

    ______________________________________                                        Liner Thickness                                                                            4.89 mm    4.85 mm  4.82 mm                                      Flange Thickness                                                                           0.47 mm    0.43 mm  0.40 mm                                      ______________________________________                                    

As is clear from the above table, the flanged portion can be preciselypressed by utilizing a liner having a predetermined thickness.

(9-2-4 Effects)

According to this invention, the flanged portion of the container bodycan be pressed so as to have a predetermined thickness with highaccuracy and, accordingly, the peripheral portion of the metallic covercan be suitably seamed to the flanged portion of the container body,whereby a container provided with a metallic cover with high quality canbe manufactured.

§10. Second Embodiment of Manufacturing Apparatus for Container providedwith Metallic Cover

10.1 Container seaming device provided with a rotary lifter and a rotarychuck

(10-1-1 Basic Structure)

FIGS. 59 to 63 represent a device for seaming a container body providedwith a rotary lifter and a rotary chuck.

A container provided with a metallic cover to be seamed by a seamingdevice according to this invention will be first described hereunder.Referring to FIG. 59, a container 370 provided with a metallic coverfilled with a content is composed of a plastic container body 371 and ametallic cover 372.

The container body 371 provided with a flanged portion 371a is formed bythermoforming a laminated material such as polypropylene/ethylene vinylalcohol copolymer/polypropylene, but the container body 371 may beformed of a sheet blank of a laminated structure and a thermally fusibleresin injected on the surface of the sheet blank. The metallic cover 372is formed of an aluminum metal or tinplate metal and provided with aperipheral edge portion 372a.

The container seaming device will be then described hereunder. Thecontainer seaming device 360 comprises a vertically movable supportingcylinder 361, a rotary lifter 362 on which is supported the container370 provided with the metallic cover supported on the supportingcylinder 361 through a bearing member 361a and a rotary chuck 363disposed above the rotary lifter 362 and adapted to hold the container370 arranged above the rotatory lifter 362 between the rotary lifter 362and the rotary chuck 363 under the pressed condition. First and secondseaming rolls 364 and 365 for seaming the container 370 provided withthe metallic cover are disposed external to the rotary chuck 363 to bemovable radially of the container 370. The seaming rolls 364 and 365freely rotate while pressing the peripheral portion 372a of the metalliccover 372 so as to roll seam the peripheral portion 372a to the flangedportion 371a of the container body 371.

A strain gauge 366 is secured to the outer surface of the supportingcylinder 361 by means of a jig 367 and the strain gauge 366 serves tomeasure the strain of the supporting cylinder 361 during the seamingoperation and detect the seaming force of the seaming rolls 364 and 365.As shown in FIG. 60, the strain gauge 366 is connected to a strainindicator 375 to which a memory recorder, not shown, is connected.

FIG. 61 shows the attachment position of the strain gauge 366. Thedistortion gauge 366 is attached to the outer surface of the supportingcylinder 361, but it may be attached to a portion A between the firstand second seaming rolls 364 and 365, a portion B near the first seamingroll 364, or a portion C near the second seaming roll 365.

(10-1-2 Function)

The function of this embodiment of the structure described above will bedescribed hereunder.

The container 370 provided with the metallic cover having the containerbody 371 in which the content, not shown, is packaged and the metalliccover is rested on the rotary lifter 362 as shown by solid line in FIG.59 under the condition that the peripheral portion 372a of the metalliccoven 372 is loosely fitted to the flanged portion 371a of the containerbody 371.

The supporting cylinder 361 is raised to raise the rotary lifter 362together with the container 370 provided with the metallic cover to holdthe container 370 between the rotary lifter 362 and the rotary chuck 363as shown by two-dotted line in FIG. 59. The rotary lifter 362 and therotary chuck 363 are then rotated together with the container 370 withthe container 370 held therebetween.

In the next step, the first seaming roll 364 moves radially inwardly andfreely rotates while pressing the peripheral portion 372a of themetallic cover 372 to carry out the first seaming operation (singleseaming operation) between the peripheral portion 372a of the metalliccover 372 and the flanged portion 371a of the container body 371.

Subsequently, the first seaming roll 364 moves radially outwardly so asto be separated from the peripheral portion 372a of the metallic cover372. The second seaming roll 365 is then moved radially inwardly androtates freely while pressing the peripheral portion 372a to carry outthe second seaming operation (double seaming operation) between theperipheral portion 372a and the flanged portion 371a.

The seaming working for the container 370 provided with the metalliccover has been completed by the cooperation of the first and secondseaming rolls 364 and 365. The second seaming roll 365 is then movedradially outwardly and the rotations of the rotary lifter 362 and therotary chuck 363 stop. The rotary lifter 362 is thereafter lowered andthe container 370 provided with the metallic cover, is taken out fromthe container seaming device.

The strain of the supporting cylinder 361 caused by the seaming rolls364 and 365 during the seaming processes is measure by the strain gauge366 and the detected strain is converted into an electric signal whichis transmitted to the strain indicator 375 to display the same inaccordance with the time elapsing. The value measured by the straingauge 366 is fed from the strain indicator 375 to the memory recorderand recorded there.

(10-1-3 Concrete Example)

A concrete example according to this invention will be describedhereunder.

The strain gauge 366 was first set to the position A in FIG. 61 toperform the calibration. Namely, an electric signal from the straingauge 366 under the non-loaded condition was read by the strainindicator 375 and recorded in the memory hycoder (FIG. 63(b)). As shownin FIG. 62, a supporting rod for supporting a weight 378 of a constantweight was mounted on the rotary lifter 362 to apply a load of 20 g tothe rotary lifter 362 and the signal from the strain gauge 366 was readby the strain indicator 375 and recorded in the memory hycoder (FIG.63(c)).

In the next step, the container 370 provided with the metallic cover washeld between the rotary lifter 362 and the rotary chuck 363 as describedbefore and the container 370 was rotated in such held state to carry outthe first and second seaming operations by means of the first and secondrolls 364 and 365. The seaming forces of the peripheral portion 362a ofthe metallic cover 362 applied to the flanged portion 371a of thecontainer body 361 in these seaming operations were measured by thestrain indicator 375 connected to the strain gauge 366 and thenrecorded.(FIG. 63(a)). As shown in FIG. 63(a), the seaming force of thefirst seaming roll 364 is represented by the F area of FIG. 63(a) andthe seaming force of the second seaming roll 365 is represented by the Sarea shown in FIG. 63(a).

(10-1-4 Effects)

According to this invention, since the seaming force of the seamingrolls 364 and 365 to the peripheral portion 372a of the metallic cover372 can be easily and exactly detected by the strain gauge 366, suitableand stable seaming working can be achieved in accordance with the valuedetected by the strain gauge 366.

10.2 Container seaming device provided with revolving seaming roll

(10-2-1 Basic Structure)

FIGS. 64 to 66 show a container seaming device provided with a revolvingseaming roll.

A container 370 provided with a metallic cover which is subjected to theseaming operation by the container seaming device according to thisinvention is composed of a plastic container body 371 in which a contentis packaged and a metallic cover 372.

The container body 371 is provided with a flanged portion 371a and isformed by thermoforming a laminated material of the structure ofpolypropylene/ethylene vinyl alcohol copolymer/polypropylene, but may beformed by a sheet blank of a laminated structure and a thermally fusibleresin injected on the surface of the sheet blank. The metallic cover 372is formed of aluminum or tinplate and provided with a peripheral portion372a.

The container seaming device will be described hereunder. The containerseaming device 380 comprises a lifter 382 which is supported by avertically movable supporting rod 382a and on which the container 370provided with the metallic cover is rested and a rotary member 389disposed above the lifter 382. The rotary member 389 rotatably supportsa chuck 383 for holding the container 370 in association with the lifter382 and the rotary member 389 also supports the first and second seamingrolls 384 and 385 for seaming the container 370 provided with themetallic cover at portions external to the chuck 383. These seamingrolls 384 and 385 are revolved around the container 370 in accordancewith the rotation of the rotary member 389 and the movable in the radialdirection. These seaming rolls 384 and 385 freely rotate while pressingthe peripheral portion 372a of the metallic cover 372 during therevolutions about the container 370 provided with the metallic cover,whereby the peripheral portion 372a of the metallic cover 372 is seamedto the flanged portion 371a of the container body 371.

The lifter supporting rod 382a is elastically supported in thecylindrical member 381 through a spring means 388. The liter supportingrod 382a is thus supported in the cylindrical member 381 through thespring means 388, so that the pressing force applied to the container370 provided with the metallic cover between the rotary lifter 382 andthe chuck 383 can be easily adjusted by changing the vertical positionof the cylindrical member 381.

An annular load meter 386 is attached to the outer surface of thesupporting rod 382a of the lifter 382 and the load meter 386 measuresthe strain of the supporting rod 382a during the seaming operation anddetects the pressing force to the container 370 applied between therotary lifter 382 and the chuck 383. The load meter 386 is connected toa load indicator 395, as shown in FIG. 65, to which a memory hycoder,not shown, is connected.

(10-2-2 Function)

The function of this embodiment of the structure described above will bedescribed hereunder.

The container 370 provided with the metallic cover is first rested onthe lifter 382 under the condition that the peripheral portion 372a ofthe metallic cover 372 is loosely fitted to the flanged portion 371a ofthe container body 371 in which the content, not shown, is packaged.

In the next step, the container 370 is raised by the cylindrical member381 together with the supporting rod 382a to a position at which thecontainer 370 is held under the pressed condition between the lifter 382and the chuck 383. The rotary member 389 rotates with the container 370provided with the metallic cover held between the lifter 382 and thechuck 383.

In accordance with the rotation of the rotary member 389, the firstseaming roll 384 and the second seaming roll 385 revolve aroundthe,container 370 provided with the metallic cover, but the chuck 383stops regardless of the rotation of the rotary member 389 while pressingthe container 370 provided with the metallic cover. At the same time,the first seaming roll 384 and the second seaming roll 385 are moved inthis order radially inwardly and rotate freely while pressing theperipheral portion 372a of the metallic cover 372, whereby the seamingoperation is performed between the peripheral portion 372a of themetallic cover 372 and the flanged portion 371a of the container body371. Namely, during the revolutions of the first seaming roll 384 andthe second seaming roll 385, the first seaming roll 384 is firstgradually moved radially inwardly to press the peripheral portion 372aof the metallic cover 372 to thereby carry out the first seamingoperation (single seaming operation) to the flanged portion 371a of thecontainer body 371. After the first seaming operation has beencompleted, the first seaming roll 384 moves radially outwardly and, inplace thereof, the second seaming roll 385 is moved radially inwardly topress the peripheral portion 372a of the metallic cover 372 to therebycarry out the second seaming operation (double seaming operation) to theflanged portion 371a of the container body 371.

The seaming operation of the container 370 provided with the metalliccover has been completed by these double seaming operations of the firstand second seaming roll 384 and 385. Subsequently, the second seamingroll moves radially outwardly and the rotation of the rotary member 389then stops. In the next step, the cylindrical member 381, the supportingrod 382a and the lifter 382 are lowered, whereby the container 370provided with the metallic cover is taken out externally to thecontainer seaming device.

During the seaming operation, the load to the supporting rod 382aapplied by the lifter 382 and the chuck 383 is measured as a pressingforce for the container 370 by the load meter 386 and the measured valueis converted into an electric signal which is then transmitted to theload indicator 395 and displayed as time elapses. The value measured bythe load meter 386 is recorded by the memory hycoder through the loadindicator 395. Since the load meter 386 is attached in an annularfashion, the axial load to the supporting rod 382a caused by the lifter382 and the chuck 383 can be exactly measured by the load meter 386.

(10-2-3 Concrete Example)

A concrete example of this invention will be described hereunder.

The plastic container body 371 was first filled with water. Thecontainer 370 in which the peripheral portion 372a of the metallic cover372 was fitted to the flanged portion 371a of the container body 371 wasrested on the lifter 382. The cylindrical member 381, the supporting rod382a and the lifter 382 were raised so that the container 370 is heldbetween the lifter 382 and the chuck 383. Under this condition, therotary member 389 was rotated to thereby revolve the first seaming roll384 and the second roll 385 around the container 370 provided with themetallic cover to carry out the first seaming operation by means of thefirst seaming roll 384 and the subsequent second seaming operation bymeans of the second seaming roll 385. During these seaming operations,the pressing force of the lifter 382 and the chuck 383 to the container370 was read by the load indicator 395 connected to the load meter 386and then recorded by the memory hycoder (FIG. 66).

As shown in FIG. 66, the pressing force of the lifter 382 and the chuck383 to the container 370 provided with the metallic cover can be easilyand exactly detected by the load meter 386 and the pressing force can besuitably controlled in accordance with the detected value, whereby theseaming operations can be suitably performed.

(10-2-4 Effects)

According to this invention, since the pressing force of the lifter 382and the chuck 383 can be easily and exactly detected by the load meter,the suitable seaming operation can be performed in accordance with thedetected value, whereby the container 370 provided with the metalliccover free from the leakage of the content can be manufactured with highprecision.

INDUSTRIAL USAGE

The container provided with the metallic cover according to thisinvention can be utilized as a food packaging container for packagingvarious kinds of foods, such as juice, fresh soft drink, jam, or driedfood.

What is claimed is:
 1. A container seaming device comprising:a turretslidably rotated on a stationary plate and having a plurality of holesfor conveying a plastic container provided with a metallic coverretained by a retainer in a manner where said retainer is slidablysupported on said stationary plate, communicating with a supply line anda discharge line, a seaming device having a plurality of seaming rollsarranged above said turret so as to surround said plastic containerprovided with a metallic cover, a lifter arranged below said turret soas to upwardly move the plastic container provided with a metallic coverretained by the retainer in one of said plurality of holes when saidturret stops, said retainer having a recess with a shape correspondingto a bottom shape of said plastic container provided with a metalliccover, and a chuck located above said lifter so as to press said plasticcontainer provided with a metallic cover against said lifter.